Should I study for tests?

I was the same as you and this attitude has paid off really badly in college, It's very hard for me to actually sit and study because I'm used to the good grades...but it doesn't work that way anymore
So I'd say do study

That's just coincidence, it happens.
You'd likely have scored even higher if you had studied.

I suggest that you sleep with the study materials and get in the 90's.

Are you a nerd? If so study.
If not then leave it.