Ironically, the only time I recall breaking off drywall screws was when my son and I were hanging drywall about 10 years ago in a 1904 flat in San Francisco. The studs were rough cut true 2 x 4 and were extremely hard and tough old growth doug fir. We broke off lots of 1-5/8 heads. On some studs we had to switch to 2-1/2" dw screws which are thicker/stronger.
I use them often with plywood casework....plywood bases and base cabinets where the screws are hidden. I can't imagine breaking off a dw screw in ply.
Scott Vroom
I started with absolutely nothing. Now, thanks to years of hard work, careful planning, and perseverance, I find I still have most of it left.