Norman Rockwell held out for a long time against using photos for reference, preferring to make charcoal studies directly from live models. The reason he finally started taking photos was to capture kids and animals, who can’t be induced to hold a pose for very long.
I’ve always admired the work from Rockwell's early period of the 1920s and 30s, but I suppose he was right about kids and animals.
Especially if you’re painting an action scene, you really have to let them act it out, and take what reference you can.
When it came to shooting scrap for a Dinotopian festival, I recruited my sons, wife, nieces, and nephews at a big family reunion to actually test out the games. We played a tug-of-war game called “Tuggle,” and a team coordination game called “Plank Walking.” The kids had fun wiping me out every time in Tuggle, because a small kid with good timing can beat out an adult every time.
Acting it out not only gave me the reference I needed (for the people at least), but it gave a reality-check for whether the games worked the way I had imagined.
The downside of using photos is that I'm easily swayed by their compelling actuality, and lured into copying the details too closely, forgetting what I had in my mind's eye. Both of my pictures fail because the clothes and the people look too contemporary, especially in their clothes and hairstyles, and not exotic enough to look Dinotopian. Maybe you can leave a suggestion for how to use photos and avoid this problem.