I've been learning classical improvisation on piano for about 4 months and my skill at playing has exploded. Ive been playing music for 15 years, and playing classical piano from sheet music for 5 or so, but learning improvise according to the strict rules of counterpoint and playing off the bass line as opposed to the chord being played forces you to attain a pretty crazy level of mastery.
This guy right here's the best, if anyone is into learning that kind of thing he's the man to learn from: https://m.youtube.com/watch?v=8DMShaqdzJg