But once somebody has done that once, it's unlikely that additional years will contribute to experience: there's a steep drop off in the marginal experience gai

But once somebody has done that once, it's unlikely that additional years will contribute to experience: there's a steep drop off in the marginal experience gained for additional time spent. That's why I wrote what I did: longer than a year or two on the same project in the same capacity is a negative indicator. It's not a deal-breaker, especially if it's just a small fraction of the employment history. If it represents the majority of the developer's history, then I expect to see significant expansion of his role as time progresses. Otherwise he's just doing the "same experience, N years over" trick, just on the other extreme end from the guy who never lasts longer than a year or so to see a project from initial development through maturity and maintenance.