Yes, I definitely do this in my books for the reason you said. I need a place for the pictures from the month that don't necessarily need their own page. And I also journal about the month to include some things that I don't even have pictures of but tell what was going on for us. I mention the events that are in the pages to come, so it feels like a little "summary" of each month, and my OCDness likes THAT
Style-wise I've done different things. One year, the left page would have a large photo and the month name and the journaling and the right page would have a smaller collage of pictures. Right now I haven't been doing one large picture like that, so what I do is similar to what you're doing now. I'll look for some that I've done. I will say that a couple of years into doing this, I really like it.