Well as a man I can say that the majority of male cam models performing solo shows are not working two-three hours straight. The customer is paying to see the build up to the money shot and you can only do that so many times in a day where it will be worth seeing. Personally, most of my solo shows run for sixty minutes at a max.
I agree that 3-4 hours at once would be too much. I take a lot of bookings ahead of time, which lets me fix a workable schedule. Some days I only model for an hour in the morning, my favorite time). Others I’ll do several shows spread through the day and evening.
I think having a show in the morning, one at night and something in between works, although it kind of takes up the whole day. A man can’t work that many hours and not feel exhausted. It’s not healthy either, in my opinion.