I’m happy to be shown that I’m wrong on any point; it would mean I’ve learned something.
I’m not a teacher. I don’t have access to a large group of guitar players to survey. However, I’ve literally never met anybody who can maintain a trill between their 3rd and 4th fingers at their maximum speed for more than a few seconds.
Personally, I could probably trill (1 2), (1 3) or (1 4) for a long time without fatigue. I’m sure I could trill (2 4) for minutes, though maybe not as long as combinations with the 1st finger. However, I cannot maintain a (3 4) trill for more than a few seconds.
I’ve spent a lot of time developing finger independence. I can comfortably maintain (1 3 4) cycles at Paul Gilbert like speeds. I’ve have practiced every possible finger combination for hammers (ascending, descending and “from nowhere”) and pull-offs. I’ve played Holdsworth lines. I can even perform (1 3 4) cycles at a Shawn Lane like speed, though as I’ve said, it quickly leads to fatigue.
The level of independence of my 3rd and 4th fingers is good, by any standard. That said, the independence of my 3rd and 4th fingers is substantially lower than that of the other combinations. Perhaps my potential for independence between my 3rd and 4th fingers is simply lower than my potential for independence with other combinations. It certainly seems so.
Maybe some people have a greater potential for independence between 3 and 4 than I have. I would believe this.
Maybe some people have people have greater potential for independence between 3 and 4 than some other combinations of their fingers. I would believe these people are a very, very small minority.
Maybe some beginner students have naturally greater independence with (3 4) and others have naturally greater independence with (2 3). That seems reasonable. I’m not really concerned with what beginning students do or do not have difficulty with. I’m concerned with the upper limits of what is feasible for an advanced player, based on anatomical and physiological factors.
I’m not discounting your post, however. Not at all. Maybe you could answer some questions for me? I’d love a teacher’s input, all other teachers are of course welcome to answer also.
Have any of your students who prefer (3 4) combinations or (1 3 4) cycles spent significant time developing finger independence between their 2nd and 3rd fingers, and yet still maintained their original preference?
Can any of your students who prefer (3 4) combinations or (1 3 4) cycles maintain a (3 4) trill at their maximum speed for an extended period (say a minute, or even just more than a few seconds)?
Have any of your students who prefer (3 4) combinations or (1 3 4) cycles developed their fretting hand technique to a very high level? For example, including (but not limited to) competence with all combinations of fingers for ascending or descending hammers and pull-offs, or perhaps some Holdsworth or Garsed style legato lines?
Can any of your students who prefer (3 4) combinations or (1 3 4) cycles perform these combinations/cycles at extreme speeds for extended periods without fatigue?
This might seem like an absurdly high standard to demand, but this is the level of playing I’m interested in.