I look at flats like they're a puzzle, and let that part of my brain have at it.
Though the only thing I don't like about flatting is cleaning up the line work. Smudges, pencil lines, and faint ink lines are my nemisis. I've learned a lot of tricks to get rid of them, but some times you just have to jump in with the eraser tool.
You should just leave the linework as is mate... colourist will always do something to them anyway really! Save yourself the time and effort unless your colouring it (i'm a big believer in only doing what you're job calls/pays for!)
Yeah I hear ya, but since I'm doing most of these flats for the color battles, I try to clean things up as much as possible for those participating. If I spend the extra time, then the colorists can get that time back to polish their color work. Call it my sacrifice.
Love your colors by the way. I'd love to learn the subtle approach you have.