My early studies were strongly influenced by Gary Karr (who I know is a controversial figure for some). Gary taught four-fingers -- definitely NOT Simandl, though. I bet Gary would say that it's not "normal" to ignore a finger.
I never use four fingers for walking. I use four fingers routinely, but not exclusively, when soloing from "seventh position" up until thumb positions. Sometimes -- for instance, playing the head to "Scrapple" -- I'll even bring it down to "fifth position." It's a challenge to get four fingers in tune, but intonation is my weak point anyway.
Four-finger technique lets me grab more, quicker. It's great for fast runs and chromaticism if you can play in tune and not stretch so hard you hurt yourself.
Here's a brief tour of the opening phrase of "Scrapple" with four fingers in motion:
http://www.chez.com/realbookonline/p...he%20apple.jpg
F# - G are 1st finger on D string, slurred & carried
Bb is 4th finger on D string
A is 3rd finger on D string
G is 1st on D
F is 4th on A
D - G - C all 1st finger, on A-D-G respectively.
Yes, it is quite a stretch, but look how fast you're getting around! I can't picture a way to play this tune as efficiently with three fingers. No doubt someone else will post something that shows how.
Have fun, and by all means, don't hurt yourself stretching.