[graypegg]

Philips in PZ screws is generally going to cam out like a regular philips head, just because you're not biting into the top with the PZ... triangle bits? I'm sure there's a technical name haha. So you can get by with that, a self-selected crappy philips experience when you could've chosen pozidriv bliss.

Philips in JIS screws is an exercise in anger management. IIRC, JIS has a much wider angle on the bottom of the drive, making it sink into the head less than a philips drive would, so it's a great way to turn your philips driver into an artisanaly-rounded single-hole punch.

[arghwhat]

Also note that drivers are made far harder than screws, so it will take many screws turned rivets before a driver becomes said artisinal hole punch.

[semi-extrinsic]

It's not the top triangle bits that cause the problem, it's that the whole geometry is different with parallel versus tapered flanks.