I just noticed an interesting detail. In 'Lower Decks', Riker says, '1200 hours, alpha shift is relieved'. Since I find it odd for the Alpha Shift to start at 0400, I'd like to imagine that Jellico may have had at least one positive effect on the ship's efficiency, and that the four-shift system may have endured. That would make sense, wouldn't it? In this system, alpha shift would go from 0600 to 1200, beta shift from 1200 to 1800, gamma shift from 1800 to 0000, and delta shift from 0000 to 0600.
Kinda neat.