Dan and Steve: track use was not limited to theaters. Track types were shipped to the factories, and got put on the next batch leaving the dock. These got sent overseas and assigned to whatever unit needed replacements. There was little to no thought about which types should go where. However, some wartime studies did look at which were better. The smooth T41s and T51s were particularly treacherous in the icy conditions of wintry Europe. Therefore the decisions to supply more grousers or to switch them out with other cleated track types.
Here's a study of different track types within the Italian Theatre
http://usarmymodels.com/ARTICLES/Tracks/trackusagefiftharmy.html
(make sure you click the links to the other pages of the article at the bottom)
You see the dizzying array of types -- mostly due to just the logistical flow from American factories -- rather than any concerted effort to try to get one type of track. They needed tanks, not track types. It'd be like if you were the supply officer of a truck company. You want truck replacements: you don't care if they have Firestone or Goodyear tires.