I think when avail is key. I have 3 nights at OKW in Feb on points and 1 on cash (no discount) . The 1 night is costing me more than my 3 nights put together. (Now if that isn't the greatest DVC advertisement, I don't know what is )
Good luck getting the discount.
BTW, if you are on cash because there are no DVC rooms available, they recommended me to be on the 7 day on call waitlist and keep checking back in the last 7 days. DVC cash ressie do not requer a deposit (just a cc to hold them) and can be cancelled 48 hours prior to arrival.