I'm probably closer to semi-pro than amateur and been playing 25-40 gigs a year, depending upon how many groups I'm officially part of, for almost 20 years now. I'm down to just 2 bands at the moment with 6-7 gigs presently scheduled for summer. Here around Denver if you're a solid player and not getting paid much for most gigs isn't an issue you could play a lot. The other sax player in the funk band I'm with at one time was rehearsing with bands every night except Tuesday including two on Sunday and playing gigs almost every Friday and Saturday night. The limitation is really how much time you have to devote and how much traveling around you're willing to do.