Pretty sure that they will not allow the same person/persons to stay at the hotel more than 30 days, regardless of number of reservations.
And, they do monitor it. We were talking with a couple last year in line at one of the rides who do 6 weeks every winter and they move resorts for one of the weeks in order to break it up.
DVC also does pay attention to the number of points someone owns and they have updated language in the RIV and beyond POS to make it clearer that being attached to any membership, even LLC's, etc. count toward your max.
