Assuming the Domme has a good online presence and a solid reputation I have no issues with a deposit. I would imagine no shows can be the bane of a Domme's existence and represent a significant loss of income. Like lawyers, doctors and accountants, a Domme's time has zero value once the that time has past.

As to some Dommes requiring longer sessions, I never book less than 2-3 hour sessions so it's really not an issue that concerns me.