With the exception of my senior year, in which I completed every assignment given to me, I rarely ever did my homework because I found it fairly insulting and boring. I knew the material, I did not enjoy getting busy work that interferred with my personal life. I viewed school as a job of sorts, and I do not like taking my work home.
Plus, I usually got high marks on my tests and that balanced out my grades fairly evenly. Not straight-As but I did get good enough grades to sustain me.