My previous boss expected me to spend time (within reason) on the forums. He considered it an investment, His reasoning was that it was 'free' training for me (training that didn't have to come out of his training budget) and also, if I saw problems on the forum then if we encountered them in our environment I'd be able to fix them way faster than I would if I hadn't seen them on the forums.

I think that he also liked that didn't ask for (demand) formal training courses as many of the others did. Personally I find them a waste of time.

These days I'm a consultant, hence no fixed hours. If I spend 5 hours on the forums one day it's 5 hours that I won't get paid for and, if there's work that needs doing, it's 5 hours that I'll have to make up somehow.