We lost 6 or seven points once. We would have given a night away to a relative who lives in the Orlando area, but it wasn't enough points for even 1 night.
I guess we have been lucky, but we have never had to cancel a trip after booking.
We are another family who planned to go only very 2 or three years. That was because that was all the points we could afford to buy at that time, but it worked out great for us. We banked and borrowed points. We have managed a two week stay one June in a two bedroom at SRR, a week that included Christmas in a treehouse, Christmas week in a two bedroom at OKW, and a couple of shorter trips to DL.