Years ago, my mother-in-law confessed that she sets all the clocks in the house a few minutes ahead, to make sure she got out the door at least semi-on time for work. The trouble was though, she knew how far ahead they were, and could compensate mentally to get the correct time. Then she would be late.
This clock would run fast, but it would do so itself, perhaps varying between 2 and 6 minutes ahead of the true time each day. You wouldn't know how far ahead it was, so you would have to plan for the worst case.
Of course, you might have other time sources, e.g. cellphone, watch, stove, microwave, etc. So, all these devices could connect via a low-power wireless LAN with a standardized protocol called Time Deception Protocol/Inaccuracy Protection (TDP/IP for short), to agree on how fast to run.-- andrewbee, Apr 11 2010random, halfbakery