This seems logical, but I've yet to experience a software shop of any complexity where you can just plug people in and out with this mercenary approach. A year or two is when I notice people actually start adding significant value, and the really high value work when you get in tune with an organization's DNA maybe still years later. Companies need veterans. If it seems like someone can't even pretend to get invested, it's a waste of time. Smart people who have a rap sheet of skills a mile long are cute, but I've personally found such peoples' dominant skill is marketing themselves...which I can't blame them for, but I think articles like this are the result of people being burned by the "mercenary" mentality.