They can and do snap and wear on the drive drums is a real issue.
Never had one snap in 50,000 miles on my Harley. It's a wear item, in the same way as engine timing belts are, but it's not one to fret about. If you worry, simply carry a spare - at least they're lighter & cleaner to stash!
Zero wear on the drive drum, too. They don't like stones though..
