Questions: self drilling/ tapping screws for chassis work

In my post I mentioned using self tapping hex head. To avoid any confusion I used the self drilling hex head, not a "sheet metal" type but the ones with the drill point at the tip. No way a sheet metal type tip will go through anything thick. Self drilling another story. they will drill through even 1/4" steel if needed. And the hex head gives a larger surface area for support. Actually I have never seen anything but hex head on self drilling. They may come in robertson or torx, but I've never seen them.