I'd go a little further and say that the actual gain is the value of your productive output minus what you had to pay for it. If you're producing $100 worth of

I'd go a little further and say that the actual gain is the value of your productive output minus what you had to pay for it. If you're producing $100 worth of value, but you spent $100/hr to get that time then you're not really gaining any ground (and you won't be able to improve your leisure time). If you produce $100 worth of value and spend only $10 to get that time, then you're producing value that can "spend" to enjoy life.