In MP's I used to get screwed at the beginning, then found places where it happens I end up past the hour. I am not a big MP fan, except for 1 place with the 3 letters, I've loved it since day 1.
As for SP's, agencies for me are the worst, the girl started counting as soon as I got in, so shower and then a little small talk and about 40-45 minutes later she tells me times up. Mind you not all agencies some I have stayed past the hour which happens rarely.
All in all I am a Indy guy, I find the ladies more at ease and less stressed, especially if there is a connection, and yes 1 time it happened that it ended up being a 2 hr session, she refused to take the money saying she should of kept track, she also mentioned that she was satisfied with the session, never heard hat again.