I had an education teacher when I was in college who told me I used the word "that" too often. I've been paranoid about overusing "that" ever since.
I had a high school English teacher who spent an entire semester making us write poems excluding the "to be" verbs. Also paranoia causing.
In the 5th grade, my teacher told me I over summarize, or included too much information in my summaries. I've felt like a failure at summarizing ever since.
Why do these things stick with us and mess with our minds?