I'm interested to know what people consider to be a 'normal' circuit.
Take a typical training aircraft, (C150/PA38) in calm conditions. Max rate of climb 500'/min (if you're lucky) at 60kt IAS.
Climb straight ahead to 500'= 1nm from the airfield. Turn left 90 degrees, continue climbimg to 1,000', level off, and trim,. Turn left another 90 degrees = 2nm from the airfield. Fly 'downwind' to a point about 45 degrees sight line to the touchdown point = 2nm from the airfield. Turn base, begin descent, set flap and start the final turn to be at 500' as you roll out of the turn =1nm from the airfield, with 500' to loose on the final approach.
Would most people agree that this is the smallest circuit that can be flown in such an aircraft, whilst at the same time, following the conventions of rectangular circuit patterns, climbing to at least 500' before turning, and being not less than 500' at the end of the final turn?
My circuit, climb to 500, turn away from the houses over water (noise abatement) turn downwind for 1/2 strut on the 172, or about 3/4nm. Level off at 1000 (usually as you are turning downwind). Turn base at 45 degrees from threshold which is about 1nm away, if that., turn final to line up with runway. Doing that gets a really nice approach angle as well!
Of course that only works for aircraft of similar performance. Low performance aircraft fly a 500ft circuit, and high performance aircraft fly a 1500ft circuit according to CASA regulations here in Aus, so naturally the lower performance aircraft should fly an even tighter circuit, and the high performance aircraft will fly a wider circuit. At our aerodrome, we are restricted due to class C airspace above us, so the max circuit height is 1000, and we overfly at 1500. Above 2000 ATC get really cranky at us.