At the end of the day the value of TAD is perhaps the fact that at least I do put in some practice when I might otherwise have just gone off with a book to read and relax. And sometimes pushing yourself a bit is a useful discipline.
I find that when I’m tired I start to just lay down leaves carelessly rather than making each stroke intentional. It becomes more the finishing rather than the process. So is the pushing still useful? Have I learned anything I didn’t already know? Somehow, I think so, though I couldn’t tell you what.