My latest revelation on gunnery has been stick scaling.
I have been working on gunnery as well. Many years in the game and I was still spraying and praying.
The Gunnery Course really helped me in a couple of ways that have been mentioned here - sight picture and unloading G's before committing to the shot.
Knowing
your stick (each one is potentially unique) and stick scaling in the game software are critical.
I've been spending a great deal of time offline practicing (another takeaway from the GC). This helps build eye and hand memory and over time builds confidence when setting up a shot. If you muff a setup, don't press. Keep up your airspeed and set up the shot again.
Of course this might not work for everybody, but I have a lot more confidence in the game, my sticks, and in me.