Crossfeed check

[LEM]

Why checking the fuel crossfeed DURING THE LAST HOUR OF CRUISE?
Checking it before the flight, on the ground, makes much more sense to me.
Isn't that a tradition without a very logical reason?

[LOKE]

There have been problems with X-Feeds freezing up - so you check it to make sure that it functions properlly when it's about as cold as it can get - last hour of cruise.

LL