Scurvy - G'day - great idea to separate this thread.
TF,
Increasing time in the circuit by requiring extra legs in the circuit creates the following problems which increase the collision risk.
(i) it increases the time in the highest traffic density areas substantially, and
(ii) it increases the density of traffic (aircraft per volume of airspace)
where there is a significant proportion of arriving / departing aircraft.
Being able to optimize scanning techniques increases the effectiveness of see and avoid, but my question is does the three legs of the circuit rule optimize it enough to reduce the overall collision risk per movement. Objective / scientific data is what I am suggesting should be considered and not just gut feelings of pilots such as me. Without a doubt mandatory use of use of radio optimizes traffic scanning far better than the three legs rule.
My closest call in the circuit was at night at YMMB (tower closed) about twenty years ago - the joining aircraft's strobes whited out my instrument panel as it joined crosswind - I was completing circuits at the time.
IMHO the downwind join with a turn opposite the circuit direction is probably one of the worst places to join the circuit - it is at this position in the circuit that distraction of setting up for landing and completing the pre landing checks is most likely to keep pilots from effectively scanning for traffic outside the cockpit.