I didn't count exactly but, a minimum of 5% of the square screw heads were too shallow and were thrown away. Even with a fresh screw and my 200 pounds leaning against the driver tip, it would start spinning in the head. I used the screws in a fence project using cypress lumber which is quite soft. I ordered a 5 pack of new driver bits with the screws just to make sure I wouldn't have any problems. I changed out the driver bits every 100 screws and still had the problem. I tried a drill driver and impact driver with no change. 5% may not sound like much until you look at the price of these.