I'm starting a new self-designed Pathfinder campaign as the DM and I'm unsure how many combat encounters I should plan each session.
The characters will start at level 1. The group consists of 4 PCs in a well-balanced group. However, the players are only mildly experienced with playing role-playing games. I plan to have them do some investigating in town and some traps/puzzles in a dungeon in addition to combat. How do I determine how many combat encounters I should run in each session?
This depends on a number of things. Do your players like to favor combat over other forms of role-playing? How long are your sessions? Do your players understand the rules well enough to where things are going to move by quickly (sounds like no, in this case)? Do you as a DM mind running a lot/a little/no combat in any given session? This sort of thing is highly customizable depending on your needs, and is thus unfortunately somewhat unanswerable.
Anyways, my personal recommendation would be to run a quick module or two before your main campaign. This will allow you to understand the sort of preparation a DM typically has for an encounter, as well as learning a couple of tricks here and there with DMing before you start your own campaign, which, in the long run, will be for the good of your story!
More importantly, it allows you to assess your player's desire for and prowess in combat. If it turns out they only make it through one encounter, then want to roleplay or ask questions or drink beer and relax for the rest of the session, you haven't wasted hours of preparation. But if they turn out to be some kind of death dealing blood-for-the-blood-god-skulls-for-the-skull-throne party, you are unlikely to run out of encounters! You don't even have to finish the module, really. Once you are confident in your ability to prepare adequately for your players, you're all good to go. Happy DMing!
Determining combat encounter frequency is best done by taste. i.e. some groups like to have lots of combat and some prefer lots of roleplaying opportunities. If your combats come too frequent, it can feel like a slog if it's more than your players enjoy. In order to get a feel for your own group's preferences, it'll help if you give them a variety of pacing for a little bit and then ask which they found more fun. Most groups are pretty flexible, though, so as long as you have some of both RP and combat, you should be fine.
One thing to bear in mind is that heavy RP sessions can feel like a waste of time because many GMs don't award XP for anything but combat. The Pathfinder rules include this little tidbit that many people miss:
Keep a list of the CRs of all the monsters, traps, obstacles, and roleplaying encounters the PCs overcome. At the end of each session, award XP to each PC that participated. Each monster, trap, and obstacle awards a set amount of XP, as determined by its CR, regardless of the level of the party in relation to the challenge, although you should never bother awarding XP for challenges that have a CR of 10 or more lower than the APL. Pure roleplaying encounters generally have a CR equal to the average level of the party (although particularly easy or difficult roleplaying encounters might be one higher or lower).
Emphasis mine to highlight the bit many miss. Giving PCs XP for pure roleplay will encourage them to indulge those scenes without getting worried about their level progression.
A good mix is between 2-4 encounters, with a healthy dose of roleplaying and fact gathering to aid the party. The best answer is to adapt to the interests of the group
The right number of encounters for any group is a function of the gm, and the average playing groups interest in combat for that particular session. If the players are more interested in roleplaying, a gm can lower the encounters to 0 or 1 per play session. Some groups love to plan and prepare carefully, or shop and interact with civilized aspects of the game world. Others prefer a focused hack and slash dungeon grind. Many of my personal favorite game sessions are outdoors/traveling games with occasional short encounters whether combat, or a fantastic encounter with potentially friendly npcs and fellow players.
In a recent module a friend of mine is running there are encounters in every room of a rather long dungeon with no options for rest (party is racing against the clock). It's challenging, but is a serious drain on the party wizard, and other limited resources.
