In the name of full disclosure, there is a slight chance that when you cancel your 11 month reservation to book the 7 month one, the 7 month villa may not be available because it was the last one and someone else was booking it at the same time. And since you cancelled the 11 month reservation (home resort) that might no longer be available either as someone might have grabbed it.
It's pretty rare, but we've seen it happen a few times as reported here. So there is some risk in the strategy unless you have enough points to hold both reservations at one time and then just cancel the one you don't need. I'd say that many people don't have that kind of quantity of points.