I have done it both ways. For me, I like doing it one piece at a time. Other then that, I am doing it the same way you are. When I clamp it, I don't have any movement either. I don't rely on the clutch alone. I have been doing this for well over 30 yrs. Not using the jig, just the woodworking.
Let's get past the clamping for now. My biggest problem is with the screws spliting the wood. When I hold the face frame flush with the outside of the cabinet and put in the screw, it is coming to within a 1/16 of an inch to the outside of the face frame. That is causing the wood to split. While the screw is not coming through, it is spliting the wood. I am already using a #7 screw. And yes it is fine thread. And no I haven't tried the #6 because as many times as I've twisted off the #7's, I can just imagine what the #6's would do. And yes, they will twist off even before the frame is sucked up to the cabinet in those cases where I can't use a clamp.
For all you guys that say this jig works fine for you, it would be nice to have someone close to me to prove it. As for my own experience, I can't say the same. Now I will admitt that I haven't used this on any other wood species. This is my first experience using the jig. And as luck would have it, I am using hickory. But, as far as I can see, I can't see where it would make any difference if I were using any other hardwood. It might be different in softwood.
I hope you are getting the help you need here. I really hope I haven't stepped on your toes. I'm still hopping someone will figure this out for me. I seem to have hit a dead end.
Maybe somebody would like to do a sample of some hardwood and see if they can duplicate what I am describing.
I am using 3/4" plywood as the box cabinet. I am planing my hickory down to 3/4" and using that as the face frame. I am keeping the outside edge flush with the outside of the cabinet. The screw is at such an angle that it is coming super close to the outside edge and that is what is causing the wood to split.
I know I am repeating myself, but I am hoping that maybe if I say it enough times, someone will see something I am missing and be able to point it out to me.
Thank you everyone that is trying to help both me and F3RR3T. I'm sure he appreciates it as much as I do.