The time between fights is used mostly for writing letters or reading newspapers.
In photo Finnish soldiers in their well warmed dugout. December 1939.

writing letters and reading newspaper

Finnish units in their positions waiting and observing for Soviet troops in Raate. January 1940

Observing

Banderole which was found from remains of Soviet Division after Raate Road
battle:
" We do not fear attacker´s threaths and we are ready to reply a strike of
warmongers with double strike."