I’ve been at a few different barns with variations of this rule. One was absolutely no jumping outside of a lesson, even trot poles or cavaletti. The barn my IHSA team was based out of in college was no jumping outside of a lesson, but we were free to set anything as poles on the ground. My current boarding barn lets anyone jump whenever, as long as there is someone else in the barn or the ring as a safety precaution. This works out well for me, because I’ve learned a ton by setting my own exercises and seeing what works and what doesn’t, and how to work through the less than perfect distances, etc.
Agree with the previous posters - you need to decide what’s a dealbreaker for you and make your boarding decision accordingly.