In my years of sailing I worked 7+7, 14+14, 21+21, 14+7, 28+14. Out of all of them 21+21 worked out the best.
The way that I always saw it was that I was working for my vacation time and working 21+21 would give you at least tow whole weeks off to do whatever you want. I always felt like I had to be ready to leave 2-3 days before CC and then once I got home I needed at least one day to decompress after returning home. Working the 12-6 watch only made it worse.
I never worked 14+28 but, I would have given my left nut to give it a try, don’t worry that’s the nut the Ex-Wife got in the divorce.