In essence I agree with this, except I feel the session should be advertised as 45 mins. I also work from home on hourly appointment basis and I make sure I give everyone a full hour, My going to pee or washing my hands doesnt come out of their time. often it means I will run 5-7 mins late as the day goes on, but I find my clients prefer that to a 45 min session. As long as its clear what is being advertised and for how long, there should be no issue.
I must be very lucky with my masseurs, as I have never had one who gave me less than the hour, often the reverse....however if it was 50 minutes and excellent I wouldn't be complaining either