I got some cabinets from a big box store for my office. They came with screws, about 3" long with big heads on them. The phillips head would strip out before the screw hit home. I ended up putting them in with 3" hex head screws. My cabinets called for 2 on top and 2 on the bottom. I guess if the cabinets were wider, then maybe 3 would be needed.
JF

I'm sure JB would say to hell with the instructions and no one is going to tell him how many and what type screws to use.... but that's another story. Sorry