Lot's - but mostly with flash. I was on a huge learning curve and between lighting courses, Neil van Niekerk and POTN I took control of my flash. It used to be the other way around. It worked fine in P mode (always went to P when the flash went on) and ETTL. FEC was a no brainer but what put knots in my stomach was repeatability. I know it gave me a decent snapshot, I just did not know how or why.
What would happen of one day I had something to shoot that counted like a friends birthday party and something did not go right. Not that would have mattered because he is a friend but you want to do your best.
A friend asked me to shoot his wedding which I repeatedly declined. Eventually I broke down and went on a 6 month learning journey to prepare. Another benefit is recovery from a problem. Now I don't stand there looking like a deer in headlights nearly as long as I used to One of the best things I ever did.