I've been pulling 5th wheels since 1998. I have never done a pull test. After I hookup I get out of the truck and visually check to see the jaws are locked. I ten lock the handle. After reading about people pulling handles of parked rigs I also check that the handle is closed and locked before I leave and do a walkaround of the rig. I do this everytime without exception regardless of the weather . Never had a problem yet. However its easy to get distracted but it you make it part of your routine you will be ok