At Eglin (bunch of restricted areas) we (controllers) would notice say a fighter getting close to a boundary and transmit to "work south" (or wherever the pilot needed to turn to stay inside) which told the pilot he was about to fly out of the restricted area. Hard for fighters to be contained some times as they're going very fast, dropping something, and then turning and burning to get out of the way of the ordinance and/or trying to remain within the restricted area. Controllers monitored the activity w/ the fighter on a discrete UHF frequency, at least at Eglin.
So even though you're technically legal flying right along a boarder of restricted areas for instance, activity could spill out. Not as big as a problem out west where they have more acreage.