I agree with you. As much as I like to cruise, I think I'd be more than ready to debark after 14 days...and more likely even after 11 days. The longest cruise we have done is 8 days and I really liked that length of time. I wouldn't mind back-to-back of a 4 night and then the 5 night on some ships.
I think I'd get terribly bored and impatient on a 46 day cruise. I guess it depends on the personality of the cruiser.