On my kid's books site, http://favoritechildrensbooks.blogspot.com/ I have about 30. I may go through later and remove some if they don't get populated with multiple posts. For now, I'm doing what makes sense and we'll see later which ones are the most useful.
Probably too many! Seventeen. The bulk of my posts are in four of them. Sometimes, something just doesn't fit any existing category and, if I think I'll blog about it again, I'll add a category. I did that just this week with youth sports.
And I just noticed a huge political problem in my household once the guys learn to read. Big Guy's story, 21 posts. Little Guy's story, 5. YIKES! I'll blame it on the fact that Little Guy couldn't talk when I started blogging.
I'd say I have 12, maybe a little less. I'm not sure if there's such a thing as too many. I want people to find what they're looking for. Many times, posts cross lines and I won't narrow it down to just one category.
I use lots of tags though!! Those are what come up in searches. I really want people to find those!!
I redid mine a while ago...I had way to many and silly things like "christmas cookies". So, I've tried to recatagorize and do bulk catagories that make sense. However, I still need to go back through and redo my old posts.
I have a lot, but because of the nature of my blog, I think they are necessary. I feature products and rooms most days, so its helpful to have them in specific categories to make them easier to find. For example, some of my categories are furniture, home office, nursery, pillows, fabrics, window treatments, etc.
I do use a lot of tags, and I cross-categorize sometimes if an item fits in more than one category, like maybe a pillow that is covered in a kid-friendly pattern would go in both the "pillow" and "nursery" categories.