M14P,
I think that accusing the schools of teaching square circuits simply to squeeze a bit more money out of proto-PPLs is a wee bit out of order.
The civilian square circuits have helped PPLs to pick their way around an airfield without bumping into each other. It's also convenient for ATC or A/G as it allows all and sundry to visualise where an aircraft actually is, or should be.
If we move on to ovals, then what do we call? "G-XX, at 120 degrees". "Roger, G-XX, call when at 265 degrees". Nah.
I'm aware that military circuits are oval, but then again a lot of military procedures are different. A run and break might be fun in a Yak 52, but probably a bit silly in a C150, don't you think?
A major reason why the civilian square circuit seems to work is that everyone is (or should be) following the same procedure. What really worries me is that some in the warbird community are beginning to follow military-style procedures (i.e. run and break) in the same circuits as merely mortal traffic. This can't be good for the health.
It seems to me that, if there's a problem with the civilian circuit, it's the fact that it's getting wider and wider.
TW