Top performers should switch jobs or assignments early and often to gain experience and build a network, and probably should not stay in a job more than 2 years

Top performers should switch jobs or assignments early and often to gain experience and build a network, and probably should not stay in a job more than 2 years until they are considered senior. Low/marginal performers need to stay in each job long enough (2 years?) to show they can hold it down and are not being let go frequently because of incompetence. Job security has value for these people who are the main beneficiaries of tenure since the more competent don't need tenure, at least until they near retirement. Middle performers can afford to switch a few times but often need to stay 4 years until their options vest. Generally the rewards are higher if you switch frequently up to a point. It's hard to get pay raises that match switching jobs.