WW2 Tanks.... A question....

[Anomalocaris]

I had a friend who was training for tank duty and he told me the average lifespan of a tank in battle was 20 seconds, IIRC.  I had to wonder why anybody would sign up for such duty.

That exaggerates.  But it is true that the life span of tanks in battle is often longer than the life span of the crew.   Penetration of tank’s armor is less likely to be fatal to the tank than the men inside.   It was not uncommon to find tanks that had gone through two or three crews.  Each time the tanks was repaired and the crew allowed to depart via the small water drain on the bottom of the hull, along with detergent and disinfectant used to mobilize the crew.

One of the reasons why winning armored battles is often so decisive is the winner, advancing after victory, can recover all the wrecked tanks he lost, wash out the remains of crew, and put most of the tanks back in service within 24 hours. The loser loses his tanks for good because all his wrecks are now behind enemy lines. So success in armored battle quickly builds on itself from a material point of view.