I always wear it, 100% of the time. I almost lost my parents back in 1984 in a wreck in which they were not wearing their belts. My Dad was an honest man and never gave anyone the [censored] story, "I'd have been killed if I'd had that belt on." He always told everyone, rightly, that he and my mother would have been MUCH better off had they worn their belts. The only thing that kept them in their car was that it was spinning and tumbling around. They hit, with great force, the dash, windows, windshield, steering wheel, and shifter, repeatedly.
I've worn mine ever since, and it has saved me from injury one time in a wreck.
I also had a friend who was killed when he was ejected and run over by his own car. No belt, obviously. It was a wreck that he very possibly could have survived, with a belt.