Why didn’t Robb just focus on Tywin?

[Chaircat Meow]

22 hours ago, Universal Sword Donor said:

When he re-releases the book with more accurate descriptions of poorly trained and poorly armed troops, I'll consider the current canon wrong. Until then, I will take the book as canon, and the SSM as semi-canon, which GRRM (and Ran) himself tells  us to do.

I'm afraid he means he might revise or change anything not already published in one of the books, not that people should go rummaging through his descriptions of clothes/armour/discipline trying to prove him wrong when he's gone on record to clarify something. 

[Universal Sword Donor]

2 hours ago, Chaircat Meow said:

I'm afraid he means he might revise or change anything not already published in one of the books, not that people should go rummaging through his descriptions of clothes/armour/discipline trying to prove him wrong when he's gone on record to clarify something. 

Why I have nothing to worry about

[cpg2016]

I mean, the way to square this circle is to look at the timelines.

Both Tywin and Robb raise their forces VERY quickly.  Tywin to begin his chevauchee across the Riverlands, and Robb to rescue Ned.  This might imply that their respective armies are, on average, better trained than might be expected.  Perhaps it is a higher composition of men-at-arms and household retainers than would normally be the case, because there was no time to raise and train levies.

This would explain both the generally poor quality of Westerosi infantry (in most fights, it's farmers with spears and not trained militia) and the fairly decent quality seen in the early stages of the WOT5K; after all, Roose's men execute a night march, with a (potentially deliberately) botched ambush, fight a losing battle, and retreat in good order.  That's a tall order even for highly trained men.