Most Dommes I know will do 60-90 minutes, so not sure where or what you're referencing.
BUT, in fairness to the Mistresses that I see, not sure why on earth you'd want only 60 minutes, and I'm afraid my mind ventures to persons that may not be good for the Mistress and their reviews/safety.

Maybe that's not fair or accurate, but the Mistresses I frequent tear me up for 3 hours and leave me wanting more,

I'd say think about what you want, maybe Pro-Dommes really aren't what you seek?