I use both. I rigged a bungee onto the end of the mojo pole where it's down on the end that gets shoved into the mud. I carry the jerk-rig in it's own bag and connect that with a caribeener. I have it set up like a trawt-line with just two or three knotted places for the decoys to clip at. I use trawt-line clips and clip the decoys on the very last thing. I really ram my pole into the mud good.
So if it's dead-calm. I'll pull on the jerk cord but if it's windy. Not so much. I use multiple mojos but not always. sometimes none.
Depends on what's working that day.
Another tip is to put panty hose on the wings of your spinners. Works on cloudy days and I just leave them on. I felt the wings we're too shiny. I read the tip in Ducks Unlimited magazine, tried it and am convinced enough to leave panty hose on my mojos.
Rick calls spinning decoys a tool and that's what they are. Jerk-string is a tool also. Having a full tool-bag and using all the tools you have in most effective manner will help you become more successful. Duck calls and decoys. The seat you use. Blind material choice. More tools.
p.s. Geese HATE spinning winged decoys.