I broke my third one about six months ago, and I never replaced it.
I'm probably weird in the brewing community, but I don't really feel the need to check anymore. I've brewed often enough and understand my equipment and process to the point where I know what I'm going to get 'close enough' for me.
Brewing is more art than science to me, and as long as I follow my process, I know I'm hitting the important numbers.
I suppose that if I ever change a component in my system (mashtun, burner or boil kettle), I'll start taking readings again until I dial that component in, but for now, I'm happy that the pale ale I make today will be the same as the one I made a year ago.