Exactly, just a little dot is enough. I was having the same problem @Todd mentioned with distorted shapes on 1 axis. Mine was on Y1, so as I cut closer to the front left, the problem got worse. If you switch to the larger head socket screw I mention, may be okay to use blue, but the purple is meant to the removable for these smaller screw.
Last thought on set screws. Actual “grub” screws or set screws are coned and dished on the bottom.
I could speculate as to why (more force in discreet area, etc.). For this use, I don’t think it is a “big deal”, the shaft has a flat spot for the socket cap screw to interface with and the second screw is apply force to lock the whole thing in place.