I am trained as a classical musician. I'm fast at reading standard notation, counting rests, all of that. Recently I played bass for a children's folk dance event. The music was mostly European dances, longways set to jigs and reels, and so on.
The form of the dances was simple; most were played AABB. Nothing unexpected. We had to play each dance a specific number of times so that the dance would end when the kids practiced, or so that each couple would be able to perform each "lead couple" role in the dance. This required us to play each form 5 or 6 times, sometimes more, including any repeats within the form.
I struggled with this and was forever losing count! I'd find myself happily playing along, and then wondering if I'd played four times already or only three. Is this simply something more experienced players have learned to keep track of, or is there a special technique?