Measure Time the Way Your Clients Do

Just a quick thought: Are you measuring time the way your clients do? 

Are you keeping track of the days (not minutes or hours) between when you first promised something and when it was finally delivered?  Are you measuring the time between your last client update and the next one?  Do you know how long -- in calendar time, not billable time -- that the average __________ takes? 

You should, because even though your clients see every moment you spend working for them on their bill, I bet they wish you'd pay the same attention to their calendar as you do to your stopwatch.