> one should instead go back up the [parent] node(s) (iterating upward when necessary) to find the next Leaf node. Nitpick: rather, you should not go anywhere,

> one should instead go back up the [parent] node(s) (iterating upward when necessary) to find the next Leaf node. Nitpick: rather, you should not go anywhere, but refer back to the parent nodes that you already have in memory, because how else did you find the current leaf node in the first place? (This also allows you to avoid round-trip latency by fetching sibling-after-next before you actually get the data in the sibling node.)