The "10000 hours rule" is the idea that people who are great at something tend to spend roughly 10000 hours getting there.  I was thinking recently, in light of my post about trusting experts, and I realized I passed the 10000-hour mark at work quite a while ago.  If there are 52 weeks in a year and you work maybe 48, and you work 40 hours per week, that's 1920 hours per year.  That means it would take 5.2 years to surpass the 10000-hour mark.  Of course not all those hours are spent productively performing the core duties of one's job.  But probably sometime between 5 and 10 years at a job, a person essentially becomes an expert. #business