When improvising, is it normal to run out of ideas quite quickly when you stick to a single scale? I just end up quoting licks over and over again after a few minutes of "good" improv. Also In terms of keys there are a few I can't improvise well at all in (I play piano) such as like B or F# coz the way the fingering is due to the scales involved is just trickier. Do you encounter these problems too?
life is a world of changes. so whatever the 'rule' was, at one moment, you will be called upon to change it soon. improvisation is a good chance to be faced with this problem, and be challenged to re-invent the context again and again. soon you may find a great scheme for making these rule changes, then of course that will stop working and you will be called upon to try a new rule-changing scheme