0 votes I guess it's true, size does'nt matter.
I've noticed that size doesn't translate at all because what's entered into the contest are digital images. Mine is a good size, about 18" by 24". But what matters for the contest is how it looks as a JPG.
I guess I could concentrate on making a bunch of smaller works instead of one big one, but then again, I'm making this stuff mainly for myself, not for the art contest prizes. But if you're concerned about it, you could probably save a lot of time and effort making smaller stuff.