I also think it's important to close down all the Waygates, as I suspect Shai'tan will be able to break the barriers between them and his prison sooner than he'll be able to get out of the Bore, in effect during the LB the Bore wouldn't be in one place and a global weakness at the same time anymore, it would become "in many places and a global weakness at the same time" - "the Blight", the DO's direct touch, would spread around the Waygates just guarded instead of "killed" by removing the Avendesora leaf... and most Waygates are near cities and stedding. The worst of that Jordan averted by having Rand close the Ways on other motives (including the most dangerous ones that would kill off much of the main cast like Elayne and Mat in Caemlyn, Egwene in Tar Valon, Tuon in Ebou Dar and end the story...), but the task isn't finished yet.