I think it would look even better, or even essential, if applied to a fanned FRETLESS. Or maybe not. Lines and simple practice would do. Don't take offense. To wit: About a year into playing, I placed some sort of adhering stickies (is that redundant?) into each space and wrote the note names on each sticky. It was a silly idea that didn't last long, not because of the bit of goo that was left behind but just because it was a silly idea. Ear and muscle memory is one's best bet.