This was a 'duh' moment for me yesterday.
I like having paired tools... Chisels that mate with router bits and so on. It helps to have the right size chisel to square up the end of a groove.
Alas, So-called 'Plywood bits' are all under-sized, to match the thickness of plywood, which is similarly under-sized. So a 1/4" chisel won't fit into a groove for 1/4" plywood, for instance, by a mere 1/64". Then I remembered that the real issue is that the plywood isn't actually made to SAE dimensions: It's metric, and sold here in the US as nominal 1/4" (15/64", or 6mm) nominal 1/2", (31/64, or 12mm), and nominal 3/4", (23/32, or 18mm).
Oh, wait. I do have those sizes. Most of my Japanese chisels are metric. Sweet! I now have router bits that pair with those chisels.
(Actually, I've had the bits for 7 years, and the chisels for 9, but only realized the correlation yesterday.)
Obviously, nobody should tell this to Wilbur Pan. He gets enough ribbing about Japanese tools and hardwoods... Japanese tools and plywoods might just be too much for him.