Code churn is an interesting measurement. I have come to realize I spend 90% of my time on 10% of the problem and I don't always know what the 10% is when I sta

Code churn is an interesting measurement. I have come to realize I spend 90% of my time on 10% of the problem and I don't always know what the 10% is when I start. This is not just true for writing software, but for installing a hardwood floor -- the center is easy and is where I naively estimate the time -- the time was really spent on the nooks and crannies.