We have rotating shifts every two months. Seniority and Performance have nothing to do with the schedule. We rotate from days, to swings, late night, another swing, and then back to days. Swings are busier, of course. So we work 2 months of days, and essentially 6 months of nights/swings. This probably didn't help at all, but this is how we do it. It keeps officers from getting burned out by working a year of night shifts.

My opinion on Senority vs Performance. I think you award bids for shifts by Senority, but you promote based on Performance. With that, though, you need to cover your busiest shifts with your most capable officers. You can't have the slow, peaceful shifts covered by all your veteran officers, and your busy shifts full of nubies. There has to be some sort of mix to make it work.