Jdvn1
Hanging in there. Better than the alternative.
I think it was a sidebar in the Epic Level Handbook, too, so it might not be RAW either. The concept was that longer prestige classes makes more of an impact on character concepts. If you take 10 levels in a class, that's more significant on your personality than a 3 level PrC. Since they don't (usually) get longer than 10, you can expand it more as a character-defining thing.