I need to add this. I you can feel any movement between the wrench and the screw, you either have a worn out wrench or the wrong size. On the smaller sizes, I frequently "sharpen' them by grinding off the shiny end. Keeping a sharp tip and flutes that are not shinny from wear will go a long way to being servicable. The smaller the wrench the bigger this problem becomes.

I like to use the Dubro #2 socket head button head screws for cowls and such. They have a very small, 1/16' or so wrench size. I have to grind the end off my wrenches after just a few uses with these screws. The socket head is shallow and with the small size, the wear is extreme. 10 or 12 screws tightened is about time for the wrench to be ground down again.

One more point, on the small size socket head set screws. They are very prone to breaking with a worn wrench. The small ones used in wheel collars and that the socket portion fully or partialy extends above the collar are very prone to cracking due to the lack of body strength supporting the threads while the wrench is trying to wedge them out. When tightening one of these small screws and the wrence "slips" a step, pull the set screw out and throw it away and replace it with a new one. The screw cracked along the socket faces and is not tightend well and may be impossible to remove later. I've see this in socket head screws up to 3/8" in size. If the set screw socket end is fully into the threads of the collar, the problem is recuced as the internal threads support the screw some what. There is still enough clearance in the thread though that you can pop the head if enough torque is applied.

Don