I am currently playing a Half-ling Rogue character with 14 INT, which means 10 skill points per level.
While it may seem a lot, actually I spend points in more than 10 skills. Rather than absolutely maximizing 10 skills and being completely useless outside of those 10, I much prefer spreading my character a bit:
- Maxed out skills: mandatory ones where the DC may be high and the penalty for failure is harsh
- 2/3 skills: mandatory ones where the DC may be high but that may reasonably be retried
- 1/3 skills: optional ones
Note: a DC may be high either because the flat DC is high (Use Magic Device is relatively high) or because it is an opposed roll (Hide vs Spot).
Of course it really depends whether your GM likes pushing you to the limits or not.
At the moment, I only have one skill that is maxed out (Use Magic Device, because it takes a lot of points to have a reasonable chance to activate an item in combat), and otherwise I thus have 9 2/3s and 9 1/3s.
For example, the Balance skill has relatively reasonable DCs (DC is 20 for less than 2 inches wide, before modifiers) and your character will always have a high Dexterity (naturally & from bonuses). Furthermore, as long as you only fail by 4 or less you do not fall, which means that the DC to avoid catastrophes is in fact 16 which requires only a score of 15. Finally, you can easily supplement your score with potions/spells for the rare cases where you really cannot afford failure (Fly, Spider Climb, ...). Balance => 1/3.
In comparison, Hide and Move Silently are opposed rolls, and once you have been spotted it is too late. It is reasonable to expect that my score in Hide is better than the opponent's Spot (especially with the Racial bonuses of a Halfling), but I do not want it to lag behind too much so those are 2/3.
In the end, it's a matter of balance between specialization and diversity. However, as the skill monkey of the group, I have found that diversity was expected of me.