in 10 years we've learned a few lessons the hard way and seen others doing similar mistakes!
hook up hoses or electrical cable still attached, slide out still extended, awning still extended etc etc. saw one guy drie off with all 4 stab jacks lowered, all four were ruined at the first speed bump.
it pays to relax and do a thorough walk around!! never rush it!
there was a recent news item about a trailer coming unhooked on the highway near our home, you can never be too careful, its almost imposible for a tt to become unhooked if its coupled properly