If I understand the system correctly, each slide can only have one "previous" and one "next". If one were wanting to create multiple presentations from one TW, however, the same tiddler might appear in different places in different presentations. For example, I usually have one TW per course I teach, but multiple presentations per course - not necessarily one per lecture, but more than one per course. My presentations might look like this:
Week1Lecture1: S1, S2, S3, S4
Week1Lecture2: S3, S5, S6
In this scenario, I miscalculated how far I would get in lecture 1, then changed my mind about what would come next (S5 vs S4). Now S3 needs different "nexts" depending what presentation it's appearing in.
Not sure how best to accommodate this scenario.