Mmm... I think 3 hours is DEFINITELY too long for a masquerade. Especially the ones where the contestants are shoved into a small, hot room with little or no water available, and of course, no one is allowed to leave because if they win an award and can't be found... Well, then what? Some costumes are too hot/big to wear if you're just sitting in a tiny room collecting sweat droplets for three hours. And it could be even worse at the cons where the contestants have their own seating section in the audience. What if their costume is HUGE, or doesn't allow them to sit? And of course, that 3 hours doesn't include the hour or two prior where the contestants have to wait around to be judged.
And I say this because, no only is my competition cosplay for next year HUGE, it will not allow me to sit, and I will have the equivalency of large wings attached to my back.
I think two, maybe two and a half hours is plenty long enough for a masquerade, but that could just be me. Few competition worthy upper level costumes are comfortable for long amounts of time, especially when you're, like I said, shoved into a small room or stuck in a chair for 2+ hours. (I can only imagine how hot you must've been in Sforza at Detour, Grandis. x.x)
I think it might help more if skit entries were just limited. And I think 2 minutes is a good time. The longer skits that take 3, 4, even 5 minutes usually bore me, especially when they're about series or characters I've never seen or even ones I dislike.
The con I went to didn't have skits. I don't believe they ever even had a stage for the contestants to walk on. I think they had a parade of costumes where all the contestants walked around... In a parade... For people to see them. But it didn't seem like anyone really cared about the competition at all. I mean, most of them went to the Star Wars panel instead.