Occasionally I have some sort of time constraint when I start a run and will usually ocnsider running faster to save some time. What an inefficient way to save what can't be more than a few minutes.
Looking a little closer, to get in a run usually requires getting dressed, walking up the street to the greenbelt trail, running for 35-150 minutes, walking home, undressing and showering, drinking, and finally eating something. Of all these activities, the actual running seldom adds up to more than 75% of the total time spent. If a run time of 60 minutes is average, and even if I run 7:30 a mile instead of 8:00 a mile, I only "save" around three minutes. And we all know how much more difficult it is to run just 30 seconds a mile faster.
Seems a lot easier to just take a shorter shower or walk faster than the difficulty of running faster. Just sayin'.