That's true, but relaxation time has value too. You could make the case (for argument's sake) that someone who works 8h/day for $30/h and sleeps 8h/day has an

That's true, but relaxation time has value too. You could make the case (for argument's sake) that someone who works 8h/day for $30/h and sleeps 8h/day has an an awake time value of $15/h. While this is definitely a frivolous and arbitrary calculation, it can be a useful metric for a busy person to figure out what his/her time is worth in terms of prioritizing activities. For example, waiting 30 minutes in line to save $3 in gas vs waiting 2 minutes and not getting the $3 savings. Those 28 minutes could have been spent doing something else, such as quality time with the kids (priceless?), etc.