Jen, there is no wordcount limit. It’s just that reading and commenting on a long piece of work is time-consuming, and it’s difficult to guess how the new member will react. (sometimes they really
can’t take it
) Once you’ve built up a network of friends who know your work you can be a bit more confident of the feedback to expect on a long piece.
I'm glad you're finding your way around, but you know where Nik and I are if you need a guide.