ADWD needed editing, and not the "oh book is too long, let's cut the ending" kind.
The "Battle of Ice" and the "Battle of Fire" should have been the main focus of the book and needed resolution. The returing POVs from AFFC should have stayed in TWOW (bar Victarion and Asha): no Arya, Jaime, Cersei, Areo Hotah. The "Golden Company" storyline is interesting but it needed more space, the reveal about Young Griff would have worked better as an Epilogue or something like that, with the invasion at the beginning of Book 6.
Cut some chapters from Tyrion riding pigs and Dany riding Dhaario and you have plenty of space to resolve the two main storylines (or at least the Winterfell one) in 900 pages
Jon, Bran, Davos, Theon, Asha and Melisandre in the North
Dany, Barristan , Quentyn, Victarion and Tyrion in the East
(am I forgetting someone?)