Finer grained self-control

[mhd]

Has anyone tried doing self-control numbers other than just 15/12/9/6, i.e. the whole spread from 6 to 15?

I'm thinking about going a bit retro for a possible campaign, as one of the RPGs of my misspent youth had mandatory disadvantages ("negative attributses"), where everyone had Greed or Acrophobia or Curiosity to a certain degree. Which was really fun, and characters weren't just looked at as having some kind of disability/affliction, but just being on a regular spectrum.

Mathematically it would just be interpolating, either between the given values or if that's a bit too uneven between the extremes, re-jiggering some costs.