My son moves a lot - he's been walking since 9 months, and we couldn't keep him in a spot. but then we get called in and the photographer was the least enthusiastic woman I've ever met. My son was super cranky because he was getting hungry and was being told no a lot. I asked if we could walk around the mall, but they basically said if we leave and they call us, we lose our spot. They were over an hour behind - so that meant entertaining my very active 1 year old in the small studio (lots of redirecting because he kept trying to get into everything). We strategically chose a window of time because it was best for him eating/napping.
We did and we walked away with no photos.