[lotsofpulp]

Marginal cost of an hour increases with each hour, at increasing rates.

If the extra time spent is causing one to lose sleep/exercise/time with kids/hobby time, I could see it being worth quite a bit more than a standard work hour.

There is also morbidity and mortality risk of commuting and commuting costs to take into account. In a car, I would put that lower bound at $0.50 per minute.