I fillet every single bluegill regardless of size. I have found yellow grubs in gills so I make sure that I fillet them all so I can see them better.
I use a pointed blade on a Rapalla 12v-110v knife. Easily do 1 per minute and when I've got a good mess, quickly work up to 2 a minute.:D
I like the flavor of skin on gills, and have probably ate a lot of grubs when I was younger. BUT, now that I know, out they go.:D Mike