I have recently changed from using three picks to four.
The reason why I changed is because I have a 12 string Uni coming my way and from what I’ve seen of C6 players and Uni players, most use four picks.
From the Uni point of view four picks gives you more range; there’s 12 strings so you need to be able to cover a greater distance.
The other reason is that the extended chords offered by C6 tuning contain more notes, so you’ve gotta be able to pick ’em.
Some C6 players use thumb strums (this is a technique I haven’t really got to grips with) but this can be done in conjunction with four picks too.
Strength and Dexterity
My ring finger is not either as strong or as dexterous as my middle and index fingers so having developed a reasonable three finger technique there was always going to be a bit of a step backwards.
I found picking exercises with metronome (my first approach to developing any technique) helped a lot. I think my ring finger will always lag behind the other two but it is becoming useful now.
What I’ve found, using four fingers, is that my technique has changed completely. I hold my right hand fanned out and move it across the strings far less. Having a thumb and three fingers available to pick with, there is usually a finger near the string I want to pick, so instead of moving my hand I just pick with the nearest finger.
One thing that I had read was good technique was sticking your little finger out while you play. I never got the point of this before. But if playing with four picks and trying to spread my hand out across the strings, the little finger tip makes more sense. It forces your hand to spread out. And it forces the picking action to come from your knuckles rather than hand or wrist movement. I think this is key to developing an efficient technique.
One of the things I had tried to achieve with three picks was alternate picking, or at least trying to be fluid and sequential with my picking rather than picking consecutive notes with the same digit. With three it was easy to run into problems, you could run out of fingers (particularly on the chromatic strings) but the extra fourth finger opens up many options.
It does however mean there are a lot more permutations of picking fingers to experiment with.
Very much related to Alternate Picking, I found that having four fingers facilitates pick blocking greatly. It is very easy to run out of fingers pick blocking, and having an extra one is very useful. Also when pick blocking you have to hold some strings down while you play other ones – the extra range comes in handy here.