In Normandy the 101 only stayed (as with the 82nd as well) in France for just under a month and was then withdrawn back to England where they were held until Market-Garden. In Market-Garden the 101 was again in action for roughly a month before being withdrawn. The same goes in the Ardennes.
Line US infantry divisions generally remained in combat continiously once committed in the ETO.
The difference in performance is that the parachute divisions never had the lenght of service on line the regular divisions had to build up their combat skill levels. Now, by this I don't want to imply that they were poor units in action. That is contrary to the record. What I mean is that truly 'veteran' units learn many small lessons about what works in combat and is necessary to win that less experianced (however well trained) units don't.
The points I made above are small ones in nature but, at the same time they show the 101 didn't know about them. Did it effect their performance? Yes, but not sufficently to cause them to fail in combat. It did however, lead them to have more casualities than otherwise would be the case.

__________________
Truth is stranger than bullshit!