The more I look at TGS and TOM, I really don't see how you could've split the four story lines there. The way you proposed it to be, it would've been something like this:
- first books is a dull story of Perrin's fighting his leadership identity and moving his camp from one muddy place to another, another book about unresolved and boring Aes Sedai politiking, Rand's going badly worse and doing basically nothing and as final "do nothing plot" we would've been reading more about Mat going to every tavern in Caemlyn; As a result, most of the readers would've hated it.
- suddenly in the second book, Perrin accepts his leaderships and we doing his awesome stuff in TAR with White Tower plot resolved out of blue, Rand became Zen and Moraine is rescued.

I frankly don't see how you could resolve better what's been resolved. Each story line resolved in TGS (Egwene uniting White Tower and Rand becoming Zen) was resolved in very nice way. I don't see how it could've been resolved in shorter chapters. Each story line resolved in ToM (Perrin, Mat and Elayne) was resolved nicely too. And again, I don't see how you could've put less chapters there as well. That means that each of story lines requires at least half a book to be resolved.

If we are to split the books by timeline - that leaves us with the first book with four storylines unresolved, but almost at the point of resolution. And all resolution for all storylines happen in the second book. Frankly I hate it much more than mere timeline inconvinience.