viewfinder diopters

[disposable@tx.rr.com]

I used one of these finders and found that the sharpest image of the focusing screen lines was when it was adjusted to a -1 diopter.

Does that imply that I should also purchase a -1 diopter lens for my late version waist level finder?

Additionally, I'm a bit curious here because I noticed in reading somewhere that the viewfinders supplied with the 202, 203, and 205 bodies had a -1 diopter from the factory.  The note I read said this was to improve viewing of the LED readout.  I'm trying to reconcile this statement with the factory suppling 0 diopter lenses with the finders supplied with non electronic bodies.  Would this perhaps be because the LED sits a bit higher than the focusing screen?

[disposable@tx.rr.com]

Should anyone else encounter this same question, for me the answer turned out to be "yes".