Anecdotal experience...

In 2005, we avoided and countered the IED threat by emplacing fire teams in covert positions throughout the AO. They were inserted usually at night, by way of dismounted patrols from our patrol base. Once curfew was lifted, the IED emplacers would come out. Anyone seen emplacing an IED was killed on sight. Suddenly, people were less enthusiastic about emplacing IEDs. The psychological impact was significant upon potential adversaries (most said, "screw that") and upon the populace (when lots of IED emplacers are shot in the chest from a single gunshot that comes out of nowhere - at least once per day - there is a sense that the Americans are now in control of security and the insurgents are dead men walking). Fewer IEDs improved our mobility, which made it easier to emplace fire teams in a wider variety of positions and continue to spread paranoia among our adversaries and reassurance among the populace.