Focus - wonderful when attained

I am sure we all have had days when you need to get 2 days of work done in 1/2 the time or less. One suddenly is able to focus with extreme acuity on the tasks ahead. It is an absolutely fabulous moment in time as tasks are completed, and decisions made. Then I wonder why isn't it like this all the time or at least more of the time? Is it the deadlines or something else? Answers anyone?