I think the page design makes a difference as well as the file sizes. If
the page is nothing BUT thumbnails, I run out of patience at about 8. If
there's a little bit of text for me to look at while the thumbnails load
I can wait for more - how many depends on how much there is to read and
how interesting the text is, but 12 - 20 would probably be safe.
Obviously, this doesn't work when people make the text part of an image
too, because then I'm still stuck waiting for it too. My connection is a
33.3 modem.