10% success rate seems way too low. Assuming the numbers aren't fudged what's your protocol?
I usually try to only go for ones marked as available as in most cases it means they are.
Then call around an hour before to two hours, usually an hour before.
I used to ask if they're available, I guess more fear of wrong number than anything else.
Now I'd only say hello i'd like to visit at such a time for such a time, is that ok, then answer any questions, usually white or black, ask to text where they at, let them know you'll call when there. Very quick and simple most times. A few variations they'll let you know. Make your way then call when there to let them know, make sure you look around and make note of some land marks so they can guide you from there. That bit is always the most taxing but after a few times it's alright.
10% flake. 90% of punts like that connect, although 10% the girl you want is actually booked but surprise they have spare girls.
It also depends how you're picking escorts as well though. Some profiles are shabby and some of us might avoid them on instinct without really knowing why. Some are very demanding, I usually avoid that, especially ones wanting deposits or identifiable details so they can blackmail you. Those are instant red flags. Unless offerring something really special or something and even then I'd probably say don't bother with extra hassle when there are easier punts.
To be fair though, I found ones with more rigorous booking processes (booking ahead rather than calling right before you set out) a bit more tricky. Ones that aren't on call it's more complex and many aren't into it full time/aren't about maximising visits.