- If someone stays less than 2 years with a company something is wrong (the person, the company or the combination).
- If someone stays longer than 4 years with a company in the same job, without promotion, that person is probably not the 'manager' type.
Both situations just give you hints on whether someone matches the profile you are searching for, but switching companies after 3-4 years seems to be reasonable for people who want to get the most out of their salaries. Nevertheless, if someone got all his 'promotions' by switching jobs you should be wary of course.
3 to 4 years is a good amount of time to switch, but I think 5 to 6 is probably better, it you have a good fit with a company. 5 to 6 years is the normal amount of time to 100% vest company 401k contributions, and any stock options. Leaving early can be a lot of money on the table.
- If someone stays less than 2 years with a company something is wrong (the person, the company or the combination).
- If someone stays longer than 4 years with a company in the same job, without promotion, that person is probably not the 'manager' type.
Both situations just give you hints on whether someone matches the profile you are searching for, but switching companies after 3-4 years seems to be reasonable for people who want to get the most out of their salaries. Nevertheless, if someone got all his 'promotions' by switching jobs you should be wary of course.