Campbell
Relaxed Intensity
Depends on the specific game, but my upper limit tends to be around 25. More than that and I have trouble reasoning about which skill to use to cover the situation. For D&D I like to keep them fairly broad. Pathfinder Second Edition and 5e have the best skill lists in my opinion, although I'm not crazy bout tool proficiency in 5e. I like characters to have a fairly low number of skills, but cover a good deal of ground so something in the range of around 15 works pretty well for that.