On the Mac, I think the combination of capability and customizability makes Keyboard Maestro well worth buying for any advanced user. Or, as the software overview describes it, "The only limit to Keyboard Maestro is your imagination!"
And while I have no idea how the information is calculated, the About dialog says the software has saved me 6 months (~4,000 hours). It may well be more than that since I've used KM for about 10 years now and that information is a recent addition.