More than you would think....about 8 out of 10 are out of spec. We are almost always able to adjust them within factory spec (1-3mm tolerances).
You must admit, original specs are a certain goal. Once manufactured , to go back and re-measure will certainly show the actual wear from work function. Anyway, I am glad to see part of your restorations have a way to measure where the frame is right now. Beautiful work you do.