Play top time, and shoulder question.

In the interest of wanting to "do it right the first time" I have a question. Ok, it's one in a long line of questions yet to come, but it's a question nevertheless.
With a Lilac Amazon Male, how much time is ok to spend on a play top on his cage? One information source says only an hour at a time, the other has no limits. Seems there is a concern that the bird may become aggressive about his play top if he spends too much time there and will want to defend it? I would think it depends on the nature of the bird, then what sort of activity he uses the play top for. Training and treats I would think are ok, just hanging out perhaps not as much.
My second question is about allowing an Amazon to ride on your shoulder. I would think it would be a no no and could lead to dominating behavior thus aggression, but you see folks doing it all the time. In falconry, you'd never allow that to happen unless your trying to train a male to donate semen for artificial insemination.
Your thoughts please,

You can keep your parrot on it's playtop as long as you like. The things you have heard of are referring to dominance behavior, which I strongly believe dosn't occur in parrots. Bird dominance dosn't exsist. Parrots, in the wild, don't want to be the "leader." they are always in a whole flock that rely on each other. If you trust your parrot not to bite you if it gets scared on your shoulder, then let it be on your shoulder. Falconry, I believe, differs when it comes to bird dominance. Sorry if I'm rambling on!

My girls is a believer in the no should no cage top rule. I've gotten away with the shoulder thing cause that's Me and Peppers gimmick she stays on the shoulder as i go about the house and she "helps" me out with the things i'm doing. Having a Pepper around has turned me into such a fruit loop. I'm actually carrying on conversations with her a she seems to actually understand. essssssssh i hope my Dad doesn't see me doing this.