This concept has popped up twice in one week, so I thought I would record it as an idea to use. And maybe it will be useful to someone else as well.
The first time was at choir rehearsal. It was phrased something like, "The better you prepare, the easier it is to improvise." In the context of music, I can confirm this. You might not know how or when the plan is going to change. But if you know it might be coming at some point, you can be ready. You can listen to recordings and role-play and hone your skills. If you play accompaniment, knowing those chords helps you to make something up if necessary. You need to know the ingredients and basic rules. +/-