In Silicon Valley, until maybe 5 years ago, I would say that 2 years per job was about the average. My average is about 2.5 years, and I've had many jobs. I've found that recently, many people, especially young people early in their careers, have been switching jobs after 1-1.5 years.

When I compare with my non-tech friends in other parts of the country, I have one friend who has been at the same job for 13 years, and one who has been at his job for 10 years. I have never held a job for longer than 4.5 years, and my shortest was 1 year.