Just to mention further evidence supporting Simon's final idea of "choosing the default timeout setting is difficult". This report recently came into bug-dejagnu precisely about different timeouts being needed on different systems: https://lists.gnu.org/archive/html/bug-dejagnu/2021-05/msg00011.html
And the replies by the maintainer reject the idea of a single timeout. No action required, just thought it was interesting that the same general issue came up elsewhere. -k