Sorry Sayagainslowly,
However, it was YOUR own comment on circuit shape that I responded to.
The military also strongly discourage extending the downwind leg. As for orbitting in the circuit - as ordered by ATC at some airfields - that is very much frowned upon. The policy is that IF you are too close to the aircraft ahead you must go around on the dead side and try again. At RAF training stations this was (probably still is) enforced by a Duty Instructor in the tower - if you transgressed you could expect to pay him a visit on landing for a telling off.
I do occasionally fly SEP from my local minor airfield and have often seen pilots who seem totally incapable of planning circuit spacing and how to fit into existing circuit traffic, especially from the overhead join.
The existing culture in this neck of the woods seems to be that if you mess up your spacing - you can extend downwind - instead of crossing to the deadside in the correct place and going around. The next pilot behind that aircraft then usually does the same and this is exactly how aircraft end up outside the ATZ!