Lubing switches — worth it, but not for the reason given

What it fixes

Stock switches often have a faint grinding feel as the stem passes the housing walls. A thin lubricant on those contact surfaces removes it. That is the whole effect, and it is a real one.

What it does not fix

A wobbly stem, an inconsistent spring, or a switch you simply dislike. Lubing an unpleasant switch produces a smoother unpleasant switch.

Amounts

Too much is worse than none: excess lubricant on the leaf slows the return and can make a tactile bump vanish. A thin film on the rails and the spring is the target.

Time

Roughly two to three hours for a full board, done properly, plus the disassembly. Whether that is worthwhile depends entirely on how much the scratch bothered you in the first place.