I've been renewing my attempts at getting good fist rotation in shadow boxing. The common wisdom is that fist remain vertical until near full extension, at which point it rotates. Often, it rotates 90 degrees into a horizontal position, but for training purposes, many people advocate rotating 180 degrees so thumb is facing down. It also helps with raising to shoulder to protect the chin. My rotation is often just 45 degrees, though I try to keep the chin beneath the shoulders nevertheless.
I came across less common advice to allow the elbows to flare out when rotating the fist for straighter elbow/fist/wrist alignment. The article acknowledges the telegraphing and lesser protection on the sides. The rationale for doing this is that when striking, you are abandoning a full commitment to defending with that arm anyway, and that telegraphing by the elbows is not much of a differentiator for advanced boxers because they are in constant motion and rely on a sense of when an opponent intends to strike.
I will never be an intermediate boxer, much less an advance one, but I do identify tried-and-true combinations that are right for me, for which I hope to build up muscle memory through shadow boxing, regularly but not for a long duration almost every day. Those are just my time priorities. So I can't afford to incorporate every possible variant of a technique or combination -- just some core ones that I pick out.
For such a limited commitment, is it better to go with arms flaring out (not a whole lot, but noticeable), or staying with the conventional wisdom of not doing that? I'm thinking about this from both a boxing and kickboxing perspective. For the latter, it may seem that one is accepting the risk of roundhouses to the torso, but I also keep in mind that the elbows flare only when striking.
In pondering the answer to this, I note that in a lot of videos, I do notice some elbow flaring, so I'm wondering if that's just the practical reality, and whether it is even worth worrying about. Here is an example of where the arm seems to be unhinging on an almost horizontal plane as opposed to the ideal vertical plane. In some boxing tutorial videos, the arm unhinges along the ideal vertical plan, with fist rotation at the end, but when the tutors speed it up, that goes away. The opening few seconds here also show unhinging of the jabbing arm along an almost horizontal plane (watch in half speed). Also 45-degree flaring here despite saying not to.
P.S. I notice that muay thai tends to have elbows out even in ready position, and some explanations is that elbows hurt incoming kicks more. I think that complicates my question too much. So please interpret my question as being about the situation where elbows are down, close to body when in ready position. It is about flaring when rotating the first for a jab/cross.