The circuit size, I feel, is more a function of allowing oneself (one's student?) sufficent time to get all those horrible radio calls, checks and the like out of the way so that you can concentrate on turning base and establishing a nice long final for a greaser landing - normally touching down about half way down the 1800 metre runway.
It is just sloppiness. It also decreases the number of circuits or landings (dependant upon whose view point!) per hour.
There are fields with stringent noise abatement procedures, I admit but most large circuits are flown because the guy/gal has forgotten the reason for keeping close to the runway.
sNr