Well this is just my thought on it, Barry can clarify. Think of the All or Nothing as fresh men and horse charging for the glory of their cause. It is wave after wave of squadrons hitting the enemy. They fought and were successful, have reformed ready for more. Now some other unlucky enemy unit has placed themselves in harms way. Your regiment can no longer produce the quick succession of wave after wave into the enemy due to losses, blown horses etc. Now its wave after wave in each bound of melee.
Lets reverse the outcome for a second and say you lost the All or Nothing melee. Thats three squadrons blown on a single charge. All or Nothing is a nice way to run thru the enemy when timed correctly. Ill timed and disaster ensues.
if the regiment formed up in line with each squadron in base contact, could they then charge as a regiment
Individually yes, not as a regiment. Not even as an All or Nothing charge. Interesting thought though.
Joe