Normally, I leave a gap when winding down the legs, so the next tractor coming under - lifts it up a bit as it does.
If a trailer is fully laden though - I wind the legs all the way down to the ground, as there might otherwise be a bit of sag in the standing trailer that would have the next tractor chump crashing into the front above the lip with their 5th wheel, if they have neglected to dip their suspension (as I do habitually…) when going under. 