I had to take a transformational grammar course for my degree (some professor's pet course). My big memory was being called out for a perfect score on a test. He said he tried to find even a minor spelling error and had no luck. I don't think the other English majors in the class were pleased with me. For some reason, people struggled with the course. I found it stupidly easy but not particularly practical for actually teaching English.

My issue isn't so much with grammar as with typos. I think and type faster than my brain proofs at times (and I suck at typing on a phone or iPad).

I used to do some diagramming with my students back in the days when I taught middle schoolers. They would diagram on individual white boards. I fondly remember students turning their white boards into protest signs: NO MORE DIAGRAMMING! LOL! One of those students is now a news anchor for a major station here, and he is a frequent supporter of our high school (his alma mater). I always have to give him a hard time. I remember him in MC Hammer parachute pants. LOL!