You are
way off about A Kou's 2v1 lasting longer. Read 558 and 559 again, A Kou put up a valiant effort but his 2v1 was over in a matter of seconds. He was quickly overwhelmed and beaten severely.
Comparatively, from 784 to 786, Shi Ryou was the aggressor pushing the action in her 2v1. She took the the fight to her enemies to keep them there and held her own without taking absurd damage. Seriously, read
785 and
786 again.
Shi Ryou's 2v1 lasted long enough for Sou'Ou and Den Ri Mi to organise reinforcements,
leave, and
make it to Ou Sen's location.
It's a nonstarter to compare who lasted longer, never mind performed better.
Granted, A Kou had much stronger opponents, but even taking that into account, Shi Ryou's performance is much better.