I love doing 3-15 photo posts with write-ups. If it's travel like I did this spring, I like showing the photos and talking about them. 15 is about the limit of an attention span. Other days, I just have a couple on a subject. One of my favourite ones to look at are the short walks. It might be a hike or a walk around the neighbourhood but you get to see things unlike what you see in travel guides.
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.