15 is probably a good number. I've noticed my art posts, when everything is put together, seems like too much all at once but it helps they've been viewed once before.

I like the photography posts a lot but for me, the photographer has to be part of the post. I always prefer personality over captions pointing out the obvious. Same with art. "Here's what I made" doesn't help me much when I don't know anything about 'I' and of course I'm not interested much in process or tutorials, since I can usually figure it out just by looking.

That's my preference. We're not all the same.