As it stands, there's nothing in the rules about this, so no. No limits. However, please be courteous. Use your best judgement. Two hundred in the space of a week is probably too much.
Oh, and I sent my request for membership in, but I forgot to mention that my book has a few "iffy" words. I mean, I wouldn't label it as mature... more like young adult. Sorry for the trouble, but I like being thorough.