Baron, that may be why you get only minor improvements with GCI - too few EW radars?
Even though the range in the MB is HUGE, I disregard that and use a "that looks right" approach when laying them out - usually 60-100nm between EW sites on a front, paying attention to the terrain and site placement. Even then, flying at just 5k AGL will usually mask out all but the nearest one...with fewer I would disappear off their network.