When I first started driving, I was taught a very brief "How to shift". It was a crude hybrid shifting with very little shifting theory. I got the chance to switch schools and my second instructor was amazing. My biggest challenge was my second instructor had to not only teach me the knowledge I needed, but also had to reverse all the bad habits from the first school.
I'm happy to hear that you found a good instructor my friend. In my years as an instructor, I've encountered those students that have to unlearn bad teaching and put in the good stuff. How's your driving career my friend? Cheers Rick