Much hot air on this thread - only Jude has got it right.
Square circuits reduce 'blind time' for high wing ac; the military does not use high wing ac for training, hence they can safely use the standard racetrack circuit which optimises the look-out for low wing ac - particularly those which fly at high AoA around the final turn. In civilian flying training there is a mixture of both low and high wing ac; hence a compromise circuit pattern is required - this is the 'square' circuit.
There is no intrinsic reason why ac flying a 'square' circuit should be out of gliding range for the aerodrome - that's basic airmanship. Although tarnished by local nosie-moaners perhaps.
[This message has been edited by BEagle (edited 24 April 2001).]