As someone that does BJJ, I wonder how sustainable this is. It's not particularly great on the body, so the idea of training when you feel like it, and then taking time off to rest through work sounds nice in theory, but the reality is that unless you've got incredible genetics or are just starting out in that white belt beginner phase, you're going to just end up hurt.

Don't get me wrong, I see it all the time, but it's not sustainable in the time it takes to get good. Ultimately you just end up as that poor twenty-something blue belt with the knees and hips of a fifty-something, still getting smeshed by higher belts.