5-7 years is pretty blanket statement. We have guys with over 20; I met two chief pilots with over 30 at their departments. One had been through huge changes, even Chapter 11, without a layoff. They had flown just about every imaginable business jet, the people stayed, the planes got bigger or smaller with cycles of the business. I worked at a NY-based department, years ago, the two pilots had been there over 30 years. Every company is unique; the ones to watch are the nouveaux riches owners, first thing to get is a plane that they really have no use for.
GF