I do one picture per post. But I nearly every post has a picture, and I usually update two or three times daily. At the same time, if I post three or four pictures it's no big deal.
The reason why I post only one picture per post is only to keep the posts even - about the same length so it fits better in the web page itself.
My blog is located at
http://rochardsbunnyranch.com/blog/ if anyone is interested.