Quote Originally Posted by bennyb View Post
One finger per scale tone, is another way of saying it. That becomes more obvious once you move out of first position, or in keys other than G, C, D and relative minors. It's a guideline, not a hard and fast rule.
Not another way of saying it, but the natural practical default, and the standard on violin (I've checked this with i.a. a bluegrass fiddler and a classical violinist), with some obvious exceptions (e.g., in the key of A there are, in 1st position, five fretteed scale notes on the g course). Check these diagrams:

http://www.the-violin-guide.com/violin-fingering.html


In the keys of G and A the two approaches are the same (in 1st position), but not in the key of Bb (last diagram). With one finger-two frets, the high eb and bb would be fretted by the same finger as the d and a, whereas in the "next scale note, next finger" the four scale notes on each course would be fretted by all four fingers. That's the natural approach as you can then transpose any scale form up (as long as you don't include open strings) the neck without revising your fingering (except bringing your fingers more closely together).