Yes, the idea is to just write a scene with a character... for me it's about getting one from my head into words, trying to inhabit their world, describe as much or as little as feels right for the character. Some characters have a lot of internal dialog, some not so much, but it's always fun to make the world around them vibrant and real, even if it's a desolate setting.
It happens to me all the time. I'm big with challenging people, but you notice I never write anything for these...
Honestly, that's mostly because I don't want anyone thinking I'm trying to rig my own system, so entering my own stuff seems silly when I'm the one running things and coming up with the challenges. But yeah, I'm terrible with procrastination sometimes, and often I hit that "this isn't good enough" point and just give up. I'm trying to get better and tell my internal critic where she can go, but...
Oh, and the word limit is more of a "guideline" really. I want people to be able to read all the entries and if I don't put something down, some entries will get out of hand. It's a problem for me more than I care to admit. Once I'm in the zone, words can come pouring out and get to be too much. I need an editor.