Roger Shoaf wrote:
"Pat Barber" wrote
For the life of me, I can't imagine the "why" on this
design.


...and the Robertson screw square head tends to snap off bits.

Really? I've never snapped off a Robertson bit or screw head, and I've
driven screws that took both hands to resist the torque of the power driver.

I can only imagine that you were either screwing into something really
hard with an impact driver (in which case it should be pre-drilled), or
else the bit had a manufacturing flaw.

Chris