Tibor Karaszi thinks about plan ages:
So what if your oldest plan is 3 only days old? Or 3 hours? Or 3 minutes?
Finding your most expensive queries based on such short “tail” is pretty meaningless and you end up wasting time tuning a set of queries that in the end wasn’t the most important ones, after all.
This isn’t necessarily something we always think about but Tibor makes a great point here.