Learning something fast requires concentration. To make sense of it all requires you to really wrap your brain around it. So does coming up with a new strategy for a perplexing sales problem or figuring out how to enter a new market.
Distractions of any sort slow your absorption of new material. Every time you jump off-topic, you waste hours of time getting your head back into the task at hand.
Yet most sellers are totally oblivious to the #1 distraction of all – checking email.