although on two major  occasions it was 90 minutes.  It's all good.

but don't ask me why. face to face i kow how it is going to go in about 5 minutes, whether there will be chemistry or not. so the 1.5 hour minimum is more so i can relax enough to enjoy the meeting. i prefer longer meetings, they do more for me.

but I have found that reviews are so good at predicting my enjoyment, that I go for 90 minutes to two hours now, unless she is too expensive.

It takes me that much time to really enjoy a gal.

With enough research, the sessions usually turn out well.

except my overnighters.  If you are worried that she will try to rob you, then, IMHO, you would not have done the proper research on her prior to making the date.  If there's no chemistry, then all you can do is hope to get your pop and beat feet out of there, I guess.  If she really 'SUCKS' as you say, you have the option to leave immediately, or grit your teeth and go ahead with the date, that choice is strictly up to you.

Face it, it's always a risk when meeting a new-to-you provider.  If you have done your homework on her, you should expect to have a good time.  But there is always the chance it will not go as expected.

Swim

The first time I see a provider I always do an hour only. I'm confident the session will go well as I've checked things out by review and back channel. Uncertainty isn't my reason for keeping the first visit to an hour. I budget and spend it on extended sessions with ladies I especially enjoy.

depends on rates. I like the providers who give discounts on multi hour rates. When I see something like 1 hr=300, 2 hr = 500, 4 hr= 800, and things like that, I would probably book multi hour appointments becaue I get more bang for the buck. When I see 1 hr = 300, 2 = 600, 4=1200, not so much of a deal. With the latter it is better to do more short dates than one long one.
In any case, I can't really do much in one hour, and I really like the non sex part of the sessions, so I do research and try to make a longer than one hour first date, then if their is chemistry, I
subsequently may do dinner dates or even overnight or daylongs.

I prefer 2 hrs. minimum.  So far, I've never encountered any problems on these longer initial appointments.  I always do my homework to try and avoid potential "problems", but I know nothing is 100% foolproof.

As for Chemistry, it's something that you can't predict until you meet the lady in person, but my instincts have never steered me wrong, yet ...LOL.

I limit myself to one hour as I find that to be the perfect amount of time to enjoy myself.

There is reason to believe that a longer engagement would be preferable.  M&G's have long been my primary resource in meeting new ladies, since it affords both of us the opportunity to meet in a social setting, and to see if the chemistry is there or can develop that can lead to a pleasing rendezvous for us both.