Resultsets are currently static, and can only be updated by query owner. Query page viewers can't know how outdated the results are, as currently no query execution timestamp is shown in the interface.
It results to situations like T213256#4926548.
I purpose to amend "Executed in xx seconds.", above resulsets, by "Executed in xx seconds at [readable timestamp]".
See also T206482: Show query code revisions and runs history for a different and more complicated but complementary approach.