Board Thread:Versus Battles/@comment-24992802-20180410223856/@comment-31165326-20180412182315

From his page.

Stamina: Superhuman (A Space Marine can remain active in combat for at least 2 weeks, can live without food even longer, can also run for days on end without a break and generally ignores non-lethal wounds. They are rarely tired or bored)

It's much more likely one of them is going to receive a fatal wound with how much time they have.