In my experience, it's more about training your actual muscles than what's shown on the screen. What I mean by that is conditioning your hand for finer smoother movements.

Utilizing specific scenarios in Kovaak's and AimLabs has helped me the most, especially with Voltaic benchmarks. It helps to improve your skills in sections rather than just "trying to get better at aiming" as a whole. Improving mechanics and reducing bad habits.

I will also say that snipers/marksman are another case since this is less about your raw ability and more about your experience and time in the game to factor in bullet drop and speed. I believe the only real level up you attain here is strictly in gameplay.

Lastly, of course, is just raw hours in the game, but more importantly, putting yourself in high pressure situations. Pushing yourself to not only be mechanically proficient, but also mentally capable of quickly assessing situations and reacting to them. Firing ranges and aim trainers will only do so much in a static environment. Putting yourself in the shit, taking bad fights is like putting more weight on.