AFAIK, there is no limit on the number of nights for which you may earn points and night credit.
It is possible that there may be a limit on the number of points you can earn per stay (Hilton has /used to have such a limit).
I'm not sure if they limit you on the number of rooms per night for which you may earn points. If you pay for them all with your Marriott credit card, naturally you will get X points/$ for all of them (X is 3 or 5, depending on the version of the card you have). Since the program is designed to reward the individual member, allowing you to get night/stay credit for multiple rooms on the same night seems to go against the stated purpose of the program.