Most of the cement board screws I've used (for installing shower tile) are square head; I've not done much shower work so I don't know if that's a trend or just

Most of the cement board screws I've used (for installing shower tile) are square head; I've not done much shower work so I don't know if that's a trend or just what the store has at the time. My fleetwood mobile home built in the late 90s was assembled entirely with square head screws, hex head lag bolts, glue, and a lot of staples.