I tend to focus on the mechanics of the gun rather than my technique or form. I think the majority of the variation in shooting comes from the gun itself, when shooting from a bench? We all occasionally pull one or fire a shot and just know we weren't on. Practicing mechanics can help to reduce those, but practice can never help improve the variation from the gun.
I've been lucky enough to have a few really accurate rifles. I can just put those guns on target, squeeze the trigger, and have bullets touching if not in the same hole (except for the occasional screw up on my part). Those guns gave me confidence in my shooting. As a result of that confidence when I get large groups I can automatically discount myself as part of the problem and start chasing down the mechanical reason(s). Now if I only knew more about dialing in a gun and the mechanics!
I think most people with experience shooting are better shots than their groups show (unless their bullets are touching). The variation in their groups come from their guns and not their technique, but that is just my opinion.
Shooting without a bench or support is an entirely different story. That just takes a lot of practice. Oh, and a retired drill Sargent as a coach that makes you do 20 push ups for every miss helps.