I believe the OP is referring to cases where members may book the Friday/Saturday that they don't need in order to be able to lock up the Sunday to Thursday stay. Those that have just enough points to book Sunday to Thursday may be at a disadvantage here.
So, basically, even though all of these people really want to arrive Sunday, some will be booking ahead of time and dropping the days to get a jump on the people waiting for their arrival date.
And yes, some people can then book on Thursday to get a jump on the Friday/Saturday bookers, and some people can book earlier, etc. Your post raises one of the issues with the new system and the walking of reservations in order to get your "foot in the door" during a non busy time and walking forward into a peak time.
You also mention that 10-11 day stay. How many people do you think are going to be able to book NYE with Christmas right before it? Those that wanted to arrive on NYE or the Day Before are now likely going to be completely out of luck -- unless, of course, they book their vacations via eBay.