The Kreg site says 1/2". Has anyone here tried material as thin as that?
Isn't the drill bit 3/8"?

I ask because I dressed up some black melamine shelves with oak trim a
few years ago and the glue I used failed. (no surprise to anyone here, I
suppose)Kreg screws sound like a convenient way to fix it, but I think
the shelves are not very thick, maybe 5/8".

I'm guessing someone will ask what the substrate is. I don't know, but
it's likely whatever combination of sawdust, glue and sweatshop tears is
current in HD's premade shelves.