It's an odd one. I can absolutely get they don't want to "act" for a long time - so much beyond 2 hours can be tiresome unless they really fancy the guy. On the other hand , yes, having multiple shorter bookings gives more variety/mitigates against the awful client & could give more income, but equally opens them up to more risk (catching something, dodgy client etc etc) if not seeing multiple regs back-back. Anyway, their rules/rates - punters will either pay them or not.