As you and a friend found out, the problem with putting that much extra effort (especially in 'concave' work) is that a promotion would usually just remove you

As you and a friend found out, the problem with putting that much extra effort (especially in 'concave' work) is that a promotion would usually just remove you from the work pool, leading to the ironic effect that the harder you work, the more likely you will limit your chances of moving up.