procastination is I guess the culprit here... But as someone who is a starter not a finisher... I find once I start something it requires a lot of concentration for me to carry through without interuption. Sometimes if it a long term project or such I loose interest after a while.
I guess this is an average.
Why the 140 and the 40? to me it takes 200% to get me to start a task and about 20% to keep up with it!