I did well in high school only studying on the train into school on the days of exams. That formula worked for me, and I figured everybody else did something similar. I knew I had to "study" for the SAT if I wanted to better than average, and practicing vocabulary during homeroom seemed like more than what everybody else was doing.
I happened to get into a good college and really struggled the first year. I studied harder than usual, but it wasn't until I started studying with some friends that I saw how much more work other people put into school.