Interesting isn't it. I had a part feral cat once too, although, until I read your doc, I didn't realize it. We adopted her as a young feral kitten. She was a sweet cat, but never quite got over some of her wildness, which really was fear. She wanted love and would see the other kitties getting it, but it was always hard for her, very, very skittish.
Just read your testing doc. Wow... such a great doc explaining what works, what doesn't work, and why. When I wrote my other reply, I hadn't read it yet, but I've come to some of the same conclusions after experience. I also learned some too. So much better if I had it up front when starting out. I have found that if I test in a couple of the same locations in the home, I'm better off. I can now show Max the "treat treat" container and shake it and show him the meter bag, so he knows what is involved, and he'll start walking to where we do his tests. He LOVES his treat treats! That's probably the biggest thing I've learned. He has to think he chose it, and then we're better off. And, as soon as I dab the drop of blood from his ear, he is up and away and ready for his treat treat. Just like you said, he has learned to sit still just long enough for one test. All of that doesn't reflect what a huge cuddle bug he is. He will jump up and lay on someone for hours and purr if they'll let him, but try and put him on your lap...no way.