NO, but it wouldn't hurt to be able to use it.
As far as shifting, to what degree of shifting skill are you talking about? How about scales and scale patterns on one string? And there are numerous fingering options (0-1-2-3--1-2-3-4; 1-2=1=2=1-2-3, ) and that's without sliding a finger from one fret to another for moving up or down the neck. Double-stops (in 3rds) scales up and down the neck. Shifting may seem hard, but once you get used to and don't have always look at the neck, you can play as fast as if you stayed in one spot with all four fingers.
Locking into one position up the neck FFCP style and staying there, is OK. But really if you are doing a tune that way, you should work it starting on a different finger each time , which means you play it in four different positions. It's
"practice", and it doesn't mean that your tune is going to sound better than if you played it in open.
But shifting, or closed FFCP boxes, you are missing half the game if you've ignored other technques -
sluring (hammer-ons, pull-offs, slides, double hammer-ons, double pull-offs, hammer-pulloff etc, etc,). If you can't separate the two hands from HAVING TO play every note with a pick-stroke, you're tunes will never fully "breathe" (the way they do when a fiddle, flute, plays them). Then there is
left-hand vibrato, some
string bending. All that can be a factor of where you do this on the neck and with which fingers you do it with. Then there is the tone aspect - will the lick sound
"better" up the neck, or will it sound better in open.
Just watch any really good guitarist, especially electric players - they are moving up and down the neck, moving from one position to another, or working licks up or down the neck on a couple of strings. "Positions" are just an interim stage; you want to go past that to where there are NO POSITIONS (or, positions are almost irrelevant) ...just the whole neck, and where you begin or end is only determined by the moment.
But if you are really going to exploit the neck, you need to have the articulation skills to put those positions to full musical use.
Every-note-with-the pick just eliminates a lot of what you might have otherwise done.
That's my view. but then, I'm not enamored of the
"every-note-with-a-pickstroke" sound. (to me, it's like a fiddle player who plays with nothing but saw strokes.)
Here are a couple solo mando things on soundcloud. I'm all over the neck, but it's to put put finger-English on the notes, or get the tone, or the phrasing/articulation. Listen or not; make up you mind if there's a valid basis to this post or not, or if it's anything that applies to the way you want to play/sound.
https://soundcloud.com/user-64352297...-solo-mandolin
https://soundcloud.com/user-64352297...ts/mando-stuff
Niles H