Say again slowly,
Sorry to diasgree with your theory but in the UK military circuits of aircraft small enough to fit inside an ATZ are oval irrespective of the aircraft type. I spent well over ten years teaching 'em and flying single jet aircraft, SEPs and Helis.
A few weeks ago a colleague of mine was telephoned by an angry FI of a local airfield. He claimed my colleague should have given way to his C152 because he was "in the circuit". Turned out he was flying bomber command sized circuits and therefore outside the ATZ at the end of downwind. As our company aircraft was on his right and outside the ATZ, the FI was in fact responsible for giving way, but his attention was off to the left with his student and the airfield.
Think about that.....