I'm new to shutterstock with about 100 accepted images up for just over two weeks (50% acceptance ratio) with about 200 total downloads.
I am very happy with the results.
  After 7-20 downloads per day, I suddenly have none.  Is it normal for sales to drop off so rapidly?

Any regular sellers who can give me an idea of a typical "curve" of download activity (not counting for seasonal ups and downs).   

I understand the need to continually upload bit by bit, but I'd hate to think that I have to upload hundreds every two weeks just to maintain sales.

Thanks