I was one of those people who didn't understand it enough to think that an increase once you got to a new bracket applied to all your income. In that situation

I was one of those people who didn't understand it enough to think that an increase once you got to a new bracket applied to all your income. In that situation, it's logical to be careful not to move to the next tax bracket accidentally. It wasn't until later that I understood that the bracket applies only to the amount of your income that is above the bracket amount. I think it's a common assumption to make if you don't research it more carefully.