Hey , about 10 yrs ago I wen to an open house at the BMW store in Cape G , Mo. After I got home I found one of the slip-ons hanging DOWN and about to fall off . ---- ! The best of us miss things all the time . If you ride with a pack , everyone look at each other's bike . IDK why , but you will see someone else's "fault" before you see your own .
It doesn't hurt to do a pre-flight , because there aren't many unnecessary parts on a bike or aircraft .