I as a general rule, fly the circuit to be within gliding distance at all times! and the aircraft i fly will reach 1000 Ft AGL before even needing to turn crosswind or within the aerodrome boundary. and there is no reason wh you cant begin a slow descent on downwind. some instructors have insisted i remain at 1000 AGL until the turn base is completed. My usual circuit at YHOX or YSBK will begin descent at late downwind, turn base approx 800 ft, final at 500.
In my initial training, in a Piper warrior/ archer and later Arrow, i was taught to keep the runway under the wing! about as far out as the taper in the leading edge. if i could see the strip past the wingtip, i was way too wide. Im not sure how some similar measurement would translate to a Cessna.
If i find myself doing a session of circuits with somone doing cross country nav circuits, will will make one the the T&G's a Stop and Go, or if its only myself and the other in the pattern, i will do an orbit on downwind. (with appropriate calls)
If an aircraft with the pattern speeds of a B737 can manage a 1.5 mile circuit, so can any GA aircraft, its all a matter of training!!!