I think we all have a default speed. On occasion i time each job (usually after a price increase) to work out the new hourly rate im attaining. I nearly always get a shock and see how much i've slowed down since last time i timed the clean which kick starts me into working faster. A new piece of equipment can have the same effect ie a new brand of pole, but it soon wears off . I guess we all have different levels of fitness/stamina also concentration so some are capable of knocking out a decent clean in less time, I've certainly slowed down as i've got older, and whilst i can speed up when i put my mind to it, i just cant keep it up (physically or mentally, i go back to my default speed. There's no right or wrong speed as long as your achieving a decent clean, were all different.
ps..this is one of the reasons im a bit sceptical about cleaning faster with hot water, im pretty sure after the initial spike in interest that using a new hot water system would bring that i would end up going back to my default speed once the novelty had worn off.