If its a flat screw head I can't see it helping with creep, could be worse if anything.
Sorry to be a bit pedantic here, but this has always bothered me:
You mean a
round-head screw
*, which has a flat bottom.
Flat-head screws generally have tapered (cone-shaped) bottoms, unless you're referring to specialty screws like "cheese heads" which are flat on both top and bottom.
It also bugs me when people conflate flat-head screws with
slotted screws, as opposed to Philips, Torx, etc. As in "hand me that flat-head screwdriver" when they're driving a round-head, slotted screw.
That should properly be called a
slotted screwdriver.
Now we'll have to see how my score compares to @TimFox's on the pedantry scale ...
* Or fillister head, or pan head, or any number of other flat-bottomed screws.