It does not help how the Navy sets watches. The Merchant Marine has 3 watches: 12 to 4, 4-8, 8-12. Repeat. In the Navy if it is like the Coast Guard you stand rotation based on how many people are qualified for the watch you stand. I have stood two man watch which is 6 on and 6 off. 3 man watch which is like the Merchant Marine, 4 man and 5 man rotation which messes with your circadian rhythm. Once even 7 man which was great. But you have to add in all hands training, operations, and other stuff during the day. After a while people are nearly zombies, just trying to get through another day. Add to this that there is a constant turnover of personnel that need to be trained and you have a really physically and mentally exhausted crew. What could possible go wrong?
When I was at sea it was a rotation of 3s.
1-1-1-32.
Eight on, eight off, eight on, 32 off.
The 32 off included all training, cleaning, maintenance etc.
And that was the best possible option.
Port and Starboard (12-12) being the normal rotation...fitting training and cleaning into the 12 off.
If one must have good sense or knowledge to post this joint would have winds echoing down the street blowing tumbleweeds.