You might try looking at it differently and consider days that you are totally gone from home- ie not touching home that day.

Consider if you had a line of flying that was groups of back to back 2 day trips you would touch home every day.

On a 3 day trip there is only 1 day of the trip that you are totally gone.

on a 4 day trip 2 days that you are totally gone. Thats why IMHO 4 days seem so much worse than a 3 day.

I know much of the quality of this depends on the duty in and duty out times of the said trips but just throwing that out there...