Zeroing/grouping for loads etc and learning to shoot/shooting are two completely different things. I am not going to zero a rifle or a handgun standing unsupported, I am going to shoot off a rest to get it close and then work from there. I believe that is what this article is about, getting the gun right not the shooter to use correct breathing, holding the gun, stance etc.
Leaning proper shooting techniques is something that cannot be learned from reading articles but imho it is taught by a qualified instructor and practiced almost endlessly to be instinctive and then refined continually.
Gatofeo's final words say everything ...
I’ve been shooting cap and ball revolvers for nearly 35 years. It took me that long to learn or stumble across the above. Print this out and file it away for future reference. What I’ve related is not an absolute; it is intended as a guide. Each gun, like its shooter, is an individual and has particular likes and dislikes.