The other thread describes how the Time Saved is calculated, so there is no point repeating that here. When you have long running, looping, or frequently executing macros, then you can get very large “Time Saved” results which are probably not accurate - or only accurate in that they saved you the time had you performed the tasks you asked Keyboard Maestro to do, which you wouldn't because it would have been impractical. Whether that makes it accurate or inaccurate is a matter for debate, but in any event the “Time Saved” is designed mostly in fun, and with only a passing degree of connection to reality.
Once we pass the AI singularity I'll ask one of the super intelligent AIs to write up some code to properly track both how much time you spend writing macros and how much time it actually saves you so it can give a more accurate result 
Of course, by then you can probably just ask your own AI to handle the tasks for you and we can all go down to the beach and take up surfing…