This is an area that I get pretty excited about. There are many ways to utilize bundles of relevant similarities to craft a well-performing application. Top three, or top five, and other metrics like the deviation of any of the top hits within the cluster all serve as jumping-off points to do some clever stuff.
On the PaLM 2 side, I love the added clarity when you can get three “candidate” results without added cost or latency. Google must have some pretty powerful parallel processing going on. Keyword extraction processes can merge candidates to get a much more complete picture, for example.