Some do it a lot, some prefer to keep their skills.
In general, PoW is dynamic game. Despite the fact it's so slow for BG. In any case, every BG manager forced to change skills from time to time... Just to be in the stream. Or something like that. 200 training points is something a little less than You need to change one skill to other...
Why. Because every man have a chance to get mistake. Even if his gladiator is BG. :)