Also arguably, you probably aren't as productive pro rata working 60 hours as you are 40. So following that to conclusion the 3 people working 40 would be more

Also arguably, you probably aren't as productive pro rata working 60 hours as you are 40. So following that to conclusion the 3 people working 40 would be more productive than 2 people working 60. There are mitigating factors to this i.e. each additional member of your headcount incurs their own cost overhead; also that certain roles and responsibilities can't be serialised so easily.