It might be true in theory that you'll be in the massage room for an hour if you paid for a 45 minute session, but it seems like a tremendous amount of women on the massage side of the biz are unaware shower time should not be included, or much more likely they simply pretend not to know...
If you pay for a 45 minute session and actually get 45 minutes of fun time and no lame, time-wasting massage before she is pressuring you to finish and / or rushing you into the shower, then yeah you have at least met the baseline requirements for a good session. But in practice girls try to cut corners on this obligation to provide a good time for the full time in a million ways.
If you know who to see you'll get a complete session, but most girls just want to get you in and out as quickly as possible and don't care how much time you've purchased. The quicker you're out of there the quicker they can be on their phone, having a smoke, getting high, or onto the next client, which is usually great by most spas since it's more $ for the girl and more $ for the spa.
Most men don't want to make a scene in a spa when they get their time cut short and rushed out of the room, and the girls take full advantage of guys who prefer not to fight with a naked woman who they want to get off with...