anything un natural for you will ultimately hold you back from improving.
I don't believe that. Mark Wilson addresses that idea in relation to his recommended stance. He says it WILL feel unnatural at first, but the more you work on it and practice it, the more natural it will feel. For me, it's natural to walk up to the cue ball and slump my body on the table in a haphazard way and shoot the shot, but I know if I go through my PSR and step into the shot in a predetermined way, which I have spent long hours practicing, I have better results.
The same could be said of the grip: for me it's natural to tighten up my grip when I hit draw, but the results are terrible. Practicing the (unnatural for me) loose grip while I am hitting draw produces better results.
Getting my chin as low as possible to the cue stick is not natural for me, rather it's something I have to work on.
A closed bridge is not natural for anyone when they first try it, and it takes a lot of hours of practice for it to feel comfortable. When I first started playing pool, I used an open bridge. As I improved, I noticed that the good players used a closed bridge, so I switched to a closed bridge. Alas, now the pros use an open bridge and things have come full circle.
I don't think a pendulum stroke is natural for anyone. It takes a lot of practice to keep your elbow still.
I think there is a lot of stuff in pool that may initially feel unnatural, but they can be practiced until they feel natural, and they will improve your game.