Demons don’t have to stand on top of a trap (if it’s on the ceiling for example), so if someone would hold a trap on top of a demon and move it around, would the demon have to follow it?
If yes, would you be able to drag them around on the ground with the trap?
So im supernatural, a partly completed trap just isn’t functional. They complete the trap, then trick/force the demon to cross into the circle. Demons can walk in just fine.
A demon that hasn’t fully crossed the trap isn’t trapped yet and can just back up.