It's been suggested that since Time doesn't exist outside the Pattern and the DO is subjected to Time only for his interactions within the Pattern, from the DO's perspective all the final confrontations with the Dragon Soul, past, present, future, appear to happen simultaneously. He can't prepare, because to Him all the variants of the closing of the Bore happen at once in an infinity of dimensions corresponding to those moments in each Turning of the Wheel.

Harriet or Brandon might know, but apparently RJ's notes more frequently told how/what things had to happen but far more rarely went into the whys (RJ knew the whys, he didn't systematically left notes to himself explaining concepts that were clear to him)

Brandon has hinted there are several things in the last three books he included without having much idea how or why they happened.

Alanna's fate is apparently such a case. Brandon said she was definitely kidnapped in Tear, but he's hinted he doesn't know more.