but everything in this little hobby doesn't make complete sense from a purely analytical point of view.
However, it is not like other businesses, and things like personal preferences and the ladies psychological make-up come into play.
She may just approach from a traditional wage point of view, as she would any other job where she is on the employee side - where you get paid the same hourly rate for hour #1 as you do for hour #2, or hour #40. If looked at myopically this way, I can see why the psychology would be "hey, an hour of work is an hour of work" and anything less than her straight hourly fee could leave a "feeling" that she is not getting her true value.
Or, she might not be sociable, and would rather spend as little time with each client as possible, and thus doesn't want to provide extra incentive for guys to make longer dates.
Or, hell, perhaps she's filling up her dance card anyway and is rolling in so much dough - so "if it ain't broke, don't fix it."
One of the fun things about this hobby is that it is a bit like the Old West. No rules. Everyone makes up their own, and does what they see fit. Just a bunch of individuals kinda winging it - not a bunch of Harvard MBAs who all come to the same cookie-cutter decisions. And truth be told, overall that is part of what makes this so much fun - even if some things might leave you scratching your head