- Shadowrun really does have a slower pace for mechanical character
development than some other games, and character development isn't showcased very well on
the character sheet itself compared with playing out scenes (that's a
big part of why multiplying Karma rewards doesn't "work" as well as
you might hope without more play time).
- Emphasis on character roles makes it plausible to be a highly
effective specialist and less plausible to be a highly effective
generalist (it's less a per-point Karma cost standard than it is an ability-to-succeed-at-tasks-in-a-category standard)
- Game sessions that are infrequent and low-intensity shouldn't be
expected to produce rapid mechanical character development under any game system
- In Shadowrun in particular character progress can and should be
represented outside of Karma rewards
Character progression considerations in general
The single most important element in balancing character progression in a TTRPG is knowledge of how long the campaign/chapter will be. Character progression should continue throughout the story (not necessarily at an even cadence) until the characters are strong enough to tackle the climax. I like to include a little bit of extra time just before the climax, so my players get to spend a bit of time being epic heroes in the world (rather than just in a final dungeon). Character development pacing should be based more on the proportion of the story that has been completed than a count of sessions that have been played.
Letting characters become too powerful too quickly is a very difficult problem to address. Many challenges become meaningless, since the PCs can deal with them so easily, but just introducing harder challenges can feel stagnant and frustrating. It just doesn't feel like you're a powerful, prime runner if every task is scaled to just barely be within your grasp, and so it can feel like your character hasn't really progressed at all.
Characters progressing too slowly can also be frustrating, but players can be distracted from it through narrative events and clever situations. Players can be presented with challenges that are still possible, with some creativity.
I think that Shadowrun's Karma system makes development feel a bit slower than many other TTRPGs because there aren't explicit character levels, and therefore no attendant Feats or Class Features that suddenly appear (at least, not as regularly). Instead players spend their Karma to incrementally become better at specific things they choose to focus on, steadily becoming better at specialized tasks rather than becoming generically more powerful at a sprint.
Progression in your Shadowrun game:
1. Character progress on the character sheet means becoming better at
things the character already does or opening new things the
character is able to do
The Shadowrun dice pool system can obscure this a little bit, but development on the character sheet means more dice for challenges, and more dice generally means more successes in tasks the characters undertake.
Examples vary by task. Being able to cast a spell at a higher Force and then shrugging off the related Drain gives a spellcaster more options in and out of combat. A Face gaining a larger dice pool for Negotiation or Con checks means more money for the group, and/or different options for making money.
Looked at from that angle, faster progression can seem kind of disjointed. Should a character really be able to go from a bumbling amateur to a competent professional in some area over the course of a handful of weeks and a single run? Maybe. It's your table, after all! But this isn't D&D, and Shadowrun system isn't designed to produce the same abrupt PC power spikes a total of 19 times over the course of the story. Instead, characters become marginally better at skill checks with each attribute increase, and those marginal improvements add up over time.
When I played Shadowrun, this was the most important piece for me. I needed to engage in a lot of skill checks, so that my larger dice pools would have enough opportunities to show better results, to feel like my character had gotten better (even though I knew from the character sheet that she definitely had improved). I feel that this particular game displays character progress through narrative, in-game successes rather than seeing stats climb to high numbers.
2. Shadowrun has much more emphasis on sandbox-style play and ancillary needs than many other TTRPGs
Shadowrun places more emphasis on things like living standards, ongoing expenses, and other "real life maintenance" elements than most games. If your players are starting as street level runners (for example), making enough money to support any lifestyle above Squalid is expected to be something of a challenge. While players are updating skills on their character sheets, they should also be solving those sandbox-like simulation elements. That setup is often a major motivation for PCs to seek out and execute runs, or risk more difficult and dangerous runs.
In short, Shadowrun players should have more to do than just max out their stats, and any improvements in their dice pools should help them do those things successfully. This is especially true if your group isn't powergaming to develop their characters as quickly as possible, and is instead focused on roleplaying elements. Figuring out how to use what you've already got to get what you still need is an important game element that is made irrelevant by rapidly improving stats.
3. Characters should develop alongside the challenges they're expected to face and at a pace that matches activity at the table
If your group were focused on executing a run every other session, with the in-between sessions used for RP and planning, they would receive more Karma and more money, and develop their characters more quickly. Newer, bigger runs become possible as the characters grow more skilled, meaning that they have opportunities to earn even more Karma and money per run. But that should be roughly proportional to the increasing Karma costs for additional specialization in skills, and the increasing cash costs of better equipment.
Conversely, if your players spend most of their in-game time roleplaying and not advancing the plot, why do they need to develop at a breakneck pace? What in-game justification would there be for their skills become sharper so quickly?
If your players do fewer of the things that develop their characters, their characters will develop more slowly. It's not unlike going to a gym. If you go there every day to exercise, you can expect to get into better shape. If you go there 80% of the time to hang out, and only exercise 20% of the time, you won't get into as good of shape over a similar span of time. Carrying out one run every three months is not naturally a high-speed development schedule.
4. Specializing is meant to be expensive
The scaling of Karma costs and training time makes this clear. Players are not intended to become elite specialists without investing time and effort in doing so, and they also aren't meant to specialize in a lot of things at once. Additionally, Attributes are among the most expensive traits characters can develop.
Minmaxing specific stats to hit high levels early requires corresponding character creation choices: if you want high Strength quickly, starting with a Troll might be an attractive strategy. It's not designed such that a generic character can easily "catch up" with a specialized one, which makes those core choices around what a character will be like much more important and distinctive.
5. Your play schedule and play style are unrelated to game mechanics
I sympathize with scheduling difficulties around games. But if your group is only able to meet twice a month, consider that it may be the relative lack of play time rather than some inherent sluggishness in the game system that is making things feel slow.
When you said
Considering that for example Strength 4 to 5 costs 20 Karma we are looking at over half a year of charakter play and about 9 play sessions just to raise one attribute.
Is this supposed to be so awfully slow or are the rewards calculated for groups who rush through 2 or 3 runs in one evening (I heard those exist).
I got a bit confused. It's not Shadowrun's fault that it would take half a year for a single attribute increase in this situation. Playing less often and playing in a way not meant to maximize Karma rewards are major factors here, in addition to Shadowrun's mechanics.
And, as above, I feel that Shadowrun is a game where character development is felt less on the character sheet than it is in actual gameplay.
Feeling progress in Shadowrun
I danced around this a bit but didn't really state my conclusions well: in Shadowrun, character progress is something that you observe through applied action more than through an abstracted rating (like a number representing character level or degree of skill in a task). Karma alone can be a disappointing way to measure character progress, as you've discovered.
In Shadowrun, specifically, that means that characters need a variety of encounters available which are tailored to their current abilities and are connected to plausible goals which can be accomplished more often than characters have chances to improve their skills.
That can take a variety of forms but my favorites are skill exhibitions and ancillary resources. These should naturally scale to your PCs' general level of prominence in the world.
- Skill exhibitions are chances for players to test their characters' skills in low-risk settings. Can they out-hack the decker they meet
at the nightclub in a friendly competition? The goal of these is to
let players engage in more skill tests without having everything ride
on success. This gives them the context to notice when those sorts of
things start to go better for them than in the past.
- Ancillary resources are things that make Shadowrunning easier, or add extra flavor to the narrative experience of the game, but are not
direct resources players will use in runs. This might be a series of
side quests in which the players locate and take possession of a
warehouse that will make a good base of operations, or establish a
data tap that will make hacking some particular group easier, but
doesn't help with hacking in general. Something like a high-end
cyberdeck, in contrast, would not be an ancillary resource as it
enhances everything any decker can do.
In the Shadowrun game I played, we started as street-level runners and so did not have the stats to do most of the "normal" game activities very well. Our GM gave us other tasks (like making contacts to more reliable, and better-paying, Mr. Johnsons, or dealing with plot points related to our characters rather than the overall story). They made perceptible differences in-game, so we felt like we were accomplishing things and moving beyond where we'd started, which was enough to tide us over until our Karma had built up enough to become more effective Shadowrunners.