First time I was real nervous and was suggesting it was probably time for me to leave and she said we still had time and cuddled up to me.
Second time I told her she'll have to kick me out, and she did 
b-
Since non-rushed service seems to be a big factor in a hobbyist's enjoyment of a session, and many good providers don't watch the clock, how does a session usually end for you guys? Is there a preferred method of ending a session? Any parting rituals?
I try to be respectful of the Lady's time. If she is no-rush, she will not say "times up". I like to take a shower afterwards, so I have to plan for that too.
If you like, you can always schedule the next date before you leave.
Always be courteous of a woman's time. Even if she does not say anything, if you notice that it is time for you to go, then get up and start getting ready. And please do not be one of the ones who not only runs far over the time you were supposed to leave, but also completely ignores any obvious clues she is sending to try to get you out of the door (ie; stretching and getting out of bed, telling you she had a good time, putting her clothes on, and then standing there waiting on you to get out of bed).
A non-rushed session does not give you license to exceed your scheduled time. It means that you expected to be mindful of the time. You will find that respect is a two way street and your actions either positive or negative will be remembered.
If you do go considerably over your allotted time (more than 15 minutes) it is always a good idea to compensate (tip) your hostess appropriately. If you take advantage of your providers goodwill do not think that she is unaware of what has happened. She is just well mannered and customers who over stay their welcomes may have to deal with that consequence if they wish to rebook.
how we are doing on time so we can check...then we know how much time we have left to play...
First time I was real nervous and was suggesting it was probably time for me to leave and she said we still had time and cuddled up to me.
Second time I told her she'll have to kick me out, and she did
b-
Ironically, in all the sessions that I have really enjoyed, I have been the one to make the first moves to wrap things up. I even had one lady pout a little (in a sexy way) when I mentioned that I should be heading out.
Of course, with very few exceptions, they aren't exactly heartbroken to see you heading out the door. But, my philosophy is that it is better to leave a little early than to have them mentally counting the seconds and struggling to keep a smile plastered to their face.
As far as parting rituals, I usually help tidy the place up a bit. Then, if it was a really great session, I fumble around trying to make sure I haven't left behind any critical items (such as car keys or cell phone) while I try to remember my name and address.
Finally, there is a small but crucial moment, the parting gesture. I have seen one provider on multiple ocassions whose goodbye body hug and sensual kiss is enough to make me want to drop my stuff, scramble for additional donation, and beg her to allow me to stay another round. Haven't succumbed yet, but there is always next time ...
All good ladies are watching the clock. If they are really good you will never know it of course. Think about it. There are certain things that you want to have happen during the session....some of them maybe a couple of times. A good provider wants you to enjoy the session and get what you came for but she also has to balance your needs with her schedule and the amount of time you have paid for. While it's true a gal may let a session run over you should not assume for one second that she doesn't realize it.
I play it by ear with my favs. My agency gal obviously has limitations on her time which is part of the reason I always book two hours so that we can relax. When it's time for her to call in I'm already in the hallway thinking about the next visit and smiling over the one that just ended.
My indie fav is a little different story. I always book her last appointment and she will sometimes hang out or we may go out for dinner if she doesn't have an early morning ahead of her.
The only real parting ritual in either case is a warm hug and a kiss goodbye with a heartfelt wish that she be well and stay safe until next we meet
You have to be aware of the subtle hints she'll give you. 8o)
I don't tie anybody up. She leaves when she is ready to. I know we're done when she starts getting dressed, not a minute before. Providers do seem to have good internal clocks. Mine is lousy. If she is hosting and there is no visible clock, I really struggle with this issue. Maybe I should leave my watch on while we're going at it.
What if you put your watch on her forehead with double sided tape?
Hmmm, now that I think about it, maybe another body part would be better...
I've done mostly outcalls, and the lady most often ends the session. She'll get up and start to get dressed, etc.
If I do an incall, I'd make sure to know the time situation, but as has been stated here, I believe the ladies are really good about giving non-verbal cues about when the session is ending. We as hobbyists have to learn to pay attention to those.