Hi there
I thought I would add a different viewpoint. You are entirely correct in the paying for time issue, but to be honest I would find it difficult to see a client for half an hour, let alone 15 mins. It takes me probably an hour to get ready for each appointment, what with shower, hair makeup etc. So, an hour appointment really is two hours, if you see what I mean.
However, if you don't mind the just out of bed look, unshowered...cool. It wouldn't be 15 mins of fun though!