RCV 'controllers' are worth their weight in gold. I did my PPL course on Cessna 150s at Cambridge in 1971 where we shared the circuit with the Chipmunks of the resident UAS and AEF. The norm in those days was to make a call when taxying out, and another when closing down, the rest of the time you kept your own lookout.
Turning final for the east west runway one day, I heard a call 'Cessna on final are you aware of the Chipmunk below you?' I banked slightly right and sure enough could just see a Chipmunk about 200ft below. We had flown round the circuit, me with high wing and he with low wing, without seeing each other although I had made the requisite 'looks' to check before turning/descending etc and I'm positive he must have done so too.