Ironically, I also was doing a vocal session yesterday and did not realize that Takes to Layers was off until we were 80 percent done. I know that the other clips still exist as they show up in the pool. Now I want to know how to make them "reappear" even if I manually have to move each to its own layer.
Update. My solution was to copy events from the pool. Then under the Edit menu choose Move to Origin to get it lined up again. Painstaking, but at least everything is there.