if it took effect too quickly, you would frequently find yourself second guessing that computerized system telling you when to be somewhere. "Oh that's right,

if it took effect too quickly, you would frequently find yourself second guessing that computerized system telling you when to be somewhere. "Oh that's right, Delta airlines hasn't switched yet but Southwest and Lufthansa have. Oh well, I'll catch the next flight." Just think of all the phones whose software updates have recently expired. No one catches on right away that their security updates stopped rolling in. But they'll definitely notice when their phone stops matching the time that they talk about on the radio.