Eldartford, you mean, 'How come the propagation delay in an amplifier causes odd-ordered enhancement and not even ordered?'
To answer this I think you have to look at the components of a square wave -odd ordered harmonics- and then look at what happens when you add a delayed inverted signal to the original signal. The result has a bit in common with what happens to a sine wave when you start adding odd-orders to it- it makes the resulting waveform wider on top and bottom, without changing the frequency. I think the only way you can interpret that is 'odd orders are enhanced'. My take on it anyway...
To answer this I think you have to look at the components of a square wave -odd ordered harmonics- and then look at what happens when you add a delayed inverted signal to the original signal. The result has a bit in common with what happens to a sine wave when you start adding odd-orders to it- it makes the resulting waveform wider on top and bottom, without changing the frequency. I think the only way you can interpret that is 'odd orders are enhanced'. My take on it anyway...