In between, a medium separator is sometimes used. If there is no spring element, movement of the drill rig would immediately place enormous forces on the drill bit and pull the drill bit off the bottom of the hole.
When drilling, a separator is occasionally used to mitigate the strain on the drill bit. If there isn't a spring mechanism, the rig's motion will immediately cause significant force on the drill bit, causing it to detach from the bottom of the well.