"Not for a long, long time" means that nearly twenty years ago, when I practiced a different flavor of TCC, a group of folks at that school decided to learn the form from the end backwards to the beginning.
We worked on it for about a year, with much help from our instructor, and we did a demonstration like that at a festival.
It was fun, it was informative and I really enjoyed doing it.
I sincerely doubt I could do it again to be honest, not without at least another year of practice and instruction.
I do mostly single form training in mirror image, though I just tried it and I can do Section 1 from Cross Hands to Opening without getting flummoxed up too badly.
I wouldn't even dream of trying Sections 2 or 3 though, too many kicks and low forms to work through in reverse.
I shudder at the thought!