Some departments at my plant have 12-hr shifts, two teams consistently days and two teams consistently nights. Two days on, two days off, two on, two off, three on, three off, repeat. Long days, but also lots of days off.
Other departments work 8-hr shifts, one team days, one team afternoon/ evening, one team nights, and one team to cover every other team's days off. Rotating shift is two or three days one set of hours, 24 hours off then two or three days the next set of hours. All new people in these departments start on rotating shift.
Management has resisted spreading the 12-hour schedule to more departments, even though more workers prefer it, because it costs more in overtime pay.
Fluoride does not kill or sterilize anything. It reacts with enamel (hydroxyapetate) to convert it to a stronger version (hydroxyfluorapatite).
People who want their enamel to be softer and wear through are welcome to drink bottled water.