Perhaps it depends upon the airfield you're at, but I can see no benefit of squaring off the circuit - only drawbacks. Now my background is predominantly military, including many hours teaching circuits to student pilots including ab-initios. I agree that the entire circuit is a valuable handling and airmanship exercise, not just the landing or take-off.
Whilst some tweaking of the circuit was allowed to cater for others in the circuit, the (racetrack) circuit was almost identical for everyone. Yes, you could extend a tad downwind, but if it was more than a 'tad', you went around, cleaned up, repositioned on the dead-side before flying your next circuit. The key decision being when to turn downwind. If the guy you went around for was now rolling, then you could comfortably turn ahead of him. If there was someone ahead of him climbing to remain then you could even turn ahead of him, as long as he hadn't started his upwind turn. Far better to trombone the upwind end of the circuit than the downwind/finals end. The final turn invariably being coordinated to put the aircraft accurately over the extended centreline at about 2-300ft (the 300ft point!). Not unheard of to get 10-12 rollers in within an hour!
I see no posible benefit from 'squaring' the circuit, it just exacerbates the chances of getting in each others way, makes the circuit longer to fly and so probably discourages a go-around being flown when you are 'getting desperate' to get at least a few t&gs in. I'm impressed to hear that some guys fly the base-leg knowing they can always make the runway in the event of a power loss!
The racetrack works perfectly well even for big (100,000lbs) aircraft and multi-piston 'bomber' type aircraft. The upwind turn (30-45deg AoB) is invariably flown at a higher IAS than finals and so - ignoring any crossing component - allows less bank (ideally 20-30deg AoB) throughout the 180deg final turn. I accept that many aircraft have a 'heavyweight' circuit where bank had to be limited and your fully-configured threshold speeds could be higher than a normal downwind speed!
Last edited by H Peacock; 2nd Jul 2017 at 14:06.