He (routinely) runs the 100-meter dash in (or
in under or
under) 10 seconds.
He ran the 100-meter dash in 10 seconds (yesterday, or routinely).
When he ran the 100-meter dash in 10 seconds for the first/fourth/last time, she agreed to marry him.
He (routinely) cooks dinner in 20 minutes.
He cooked dinner in 20 minutes (routinely or yesterday).
When he (finally) managed to cook dinner in 20 minutes, she agreed to marry him.
But
“When the car broke (or breaks) down, the volcano erupted (or erupts)” is grammatical but odd. The canonical “when” not only sets up a common temporal frame for the situations presented in both clauses, but also prepares us for a relationship between them.