Thanks for all the advice so far! I appreciate the help. I agree that it may seem like I'm overthinking this, but I do have my excuses for doing so. It does start with some stuff that Hwansik Kim has been talking about. I really want to get a video up here demonstrating some stuff, but I haven't been able to make that happen all year.
In short, I've spent a lot of time playing around with grip through the years, and I've spent a lot of time playing with "grip strength" and how hard to grip a gun. I had been almost universally disappointed with my performance. None of the general "tips" or ways that people described working with things tended to make sense. A lot of it emphasized locking up various parts of the body, or not locking them up, and a common theme that tends to emerge is some degree of grip strength and keeping the gun from jumping around in your hand. However, I've never found those things to really work well for me.
Going with the lists of things mentioned below, things like pressure rear to front and side to side with the clamshell type grip or rolling the palms up and so forth are all things that I can do, but they result in what I would consider marginal improvements in second shot control. After I reach the point where the gun doesn't move in my hand, that's where the problems on progressing start.
If I don't let the gun move in my hand and I am reasonably relaxed, then I can get very consistent tracking and movement of the gun, but there is waay too much recoil and muzzle rise/gun movement vertically at way too slow a speed to get fast follow-up shots. It is consistent, but not fast.
I've found that increasing grip strength applied to the gun (or at least framing it like that) does just about zero for my recoil control, and can often decrease trackability or "flatness". Before Hwansik Kim, everyone emphasized grip strength so much (except for a few outliers that were focusing on other shooting requirements beyond the speed of a second followup shot) that it was a little frustrating. However, hearing some of his analysis of locked wrists was one of the first major breakthroughs I've had in a while. I think his analysis of the confusion of grip strength and locked wrists as discussed above are spot on.
People kept talking about a strong grip as somehow keeping the gun from rotating, but I've never found this to be the case. I can grip as strong as I can on a pistol and my wrist will have only slightly decreased range of motion and resistance. I didn't realize that for most people, apparently, but gripping hard, you lock up your whole wrist and oftentimes the elbow, too. For me, these are entirely independent activities, as are most of the other muscles. But when I tried Kim's advice of not worrying so much about grip strength and emphasizing the reduction in vertical and horizontal movement through even pressure and the appropriate muscular tension in the wrists, particularly in the pinky side of the wrists, I saw marked improvements in trackability and recoil control. However, it's just the tip of the iceberg, and I know that I have a long way to go.
And so this is really my reason for appearing to overthink this, because the "simple" advice doesn't work for me. For whatever reason, I'll mostly operate the majority of the major regions of muscular control very independently from one another from what other people are self-reporting their behavior to be. I also find that things like "clamshell" and "rolling over" and the like often interfere with my muscular tension to the point that it unlocks muscles and all sorts of other things, leading to a mild case of limp wristing. So the general advice isn't "effective" for me because my interpretation of that advice doesn't seem to lead to the intended results, except for marginal improvements occasionally to the point that I can't assign causation.
I continue to put many rounds of practice in to track this behavior and try to fix things, but I have a limited amount of time at the range, and I have to do a lot of "self analysis" in dry time to maximize my time on the range, which is why I am going so "over thinking" on this. I need to know what the real causes are to recoil control, so that I can manifest that in my own body accounting for my own nervous system behaviors, because the "intuitive shortcuts" such as "grip the gun hard" don't actually work for me (for gripping hard, I can grip the gun as hard as I can to the point of shaking and still see almost the same amount of muzzle flip as without a strong grip). Thus, I'm trying to figure out exactly what really needs to happen and how to achieve that, and I'm looking for some "perspectives" to try to get some progress made more efficiently rather than trying literally the millions of possible variations under the sun to get where I want to go.
I appreciate all the thoughts and advice you can give. I just wanted to give some context to this. I've found the "over analyzing" approach of Hwansik Kim has netted me the most significant gains across the board, with Leathem's and Langdon's trigger control advice second.
If I'm honest, what I really need to do is get to Langdon's or Kim's classes and get some diagnostic advice from them in person, but until then, I have to keep trying to make progress with the help of those at a distance.