We've been pulling our 5ver for just over 5 years....I have done a pull test EVERY time I hook up....we still follow a checklist....sure we know what we're doing...but, safety comes first. I use to use a lock on the pull bar...but don't anymore. If we stop, I check to make sure nobody has pulled it. I also have 2 of my bed rail pins locked...have heard of those getting pulled also.
I do the light, break, blinker check every time also.
I guess all of this caution comes from my job testing helicopters.