I recently come out of an intense month where very focused company objectives needed to be achieved.
Reaching these objectives were priority one, two and three.
Then the world changed. Objectives were achieved and I went back to my usual speed and approach to selling.
Varying your work speed is similar to exercise. You cannot sprint 100% of the time. Your performance will drop and eventually you will burn out.
I believe the trick is carefully planning the times when the intensive work is required, and working at an efficient and effective pace at times inbetween.
By varying your speed your mind will be fresh and over time you will be more effective!