What is the worth of an hour of your life?
makecheck: I think the best guideline is to imagine the percentage of time someone has to work.  Although some people are lucky enough to work reasonable hours for high pay, many are not.  Assume that an hour of their free time is basically priceless.Having said that, some people will also be more efficient.  Imagine if you have a car, versus walking or using a bus; you might complete 5 errands in an hour by car, that wouldn't be possible without a car.  To "save an hour" means different things to these people.Time can even be a bit of a paradox.  If you make a task 1000 hours faster, you don't necessarily "save" 1000 hours of free time, due to multi-tasking.  Consider a small, repetitive task.  If it takes a few minutes to finish, I will switch to something else, or maybe go get a drink, effectively compressing the elapsed time to zero.  Whereas, if it takes just a few seconds, I'll probably sit and wait, which is dead time.  In the end, I'll waste more time on the "faster" task than the slower one!