This is question for the ladies, mainly...though I'm sure some of you guys will have interesting perspectives, as well.  The question is NOT about going overtime--i.e., "She certainly is not a clock-watcher; we went over by 20 minutes."  Rather, it's this:

I am just a massage guy so keep that in mind.  Most places I've been to have a clock on that is easily viewable. Sometimes it's  even a very small digital clock in an inconspicuous  location. Many providers will play a music set and know the time based on songs. Some will just look at or tap their phone to see time. Some will set phone to vibrate or sound like a text at the 10 or 15 minute  mark.  I, too, have had one or two set an alarm as you did. Definite no repeats there. A few places I've even had someone knock on the door to let the provider know  time was  up. And there are a few places around  where the clock is ALWAYS 7-8 minutes ahead. I used to say nothing, but after waiting 5-7 minutes for a girl to return, I was sometimes almost 15 minutes in to an hour session before she even touched me.

I think most either have a view of the clock or use some signal such as setting there phone etc. The most interesting I've been aware of was a cloths dryer that seemed to always end it's cycle when the session ended.

I prefer if they have a clock easily visible.  Because I have to manage my time as well.  At my age I get one shot and prefer to keep it until the very end

Wear a watch and check behind a guys back

You will never lose track of time with a watch on your arm.

....I'm mostly an AMP guy nowadays and, yes, there's a big wall clock on prominent display in most AMP's.  Some are set 10 minutes fast.  At some AMP's, the guy's 60 minutes begins the minute he gets out of his car, it seems, and he ends up getting 30-40 minutes for his "hour."  At others, it's closer to the actual 60 minutes.  With some of my faves, it always seems to go over by 10-15 minutes.

It's an internal clock we have inside.  I don't do hour appointments unless it's a regular and I have an incall already set up, so I do have a difficult time judging 60 mins.  It goes by SO fast!
I never look at a clock though.  It's definitely rude.  I tend to go over a bit because I like chatting and learning something from the men I hangout with.
I only see one person a day so I'm never on my way to another appointment so there's generally no need to rush afterwards.  
I do like it when ladies post in their ads that they're not clock watchers.  I personally don't post that but it's sort of a given.
When you have a 2 hour minimum it's about creating a whole experience that can't be done in a shorter meeting.  That's the plus side...though it costs more!
Connecting with each other is really an important aspect to this hobby.  Even if it's just a one time meeting...making it special is an art form.  Clock watching destroys that

My magic way of telling the time is listening to music. I have specific albums I like to listen to, and I know by the song that's playing how much time has passed. I also have a really good grasp on most song times and regardless of what Im listening to I know how much time has passed by how many songs have played. I feel like Bruce Willis' character in Hudson Hawk, haha. I have a clock in the room but I think it's rude to look at it. If I have another client on the way (rare, since I prefer the one-a-day method) I will wrap things up on time in a suave way and make sure everyone's happy with enough time for a relaxing, soothing clean up. I have been known to go over though. It happens.

There is no clock at my Incall.  

Re: discreet vs. discrete:

I've actually had a provider use one of those white kitchen timers with the dial that tick away the seconds.  It was so loud and a complete turnoff.  I couldn't continue the session and I actually quit before the DAMN bell went off.

That's hilarious, Tom!!!