I've mentioned it before, but I'd highly recommend The Tank War by Mark Urban. It tells the story of 5 RTR from the Battle of France right through to the invasion of Germany based on the regimental war diary and interviews, diaries and correspondence of the tank crews themselves. There are a reasonable number of crewmen who were on active service throughout the entire war.

In British (and I believe also US) service, however, it was a very common practice to actually tranfer the most experienced and veteran troops off the line and send them to train new recruits so that their experience and knowledge could be more effectively passed on, and incidents of fatigue could be reduced.