In the 4 month window from 11-8 months before arrival, there is no competition for Riviera owners. Like Sandi said, at 7 months, all bets are off. And there's no guarantee that owners will get the exact dates / room size / view that they may want even when booking 11 months out. (Still, if you browse 8-11 month availability across all resorts, it's probably not as dire as some posts suggest. Not every resort owner is rushing to book their trips nearly a year out. Some dates are very popular, many others are not.)
People would be unwise to buy resale at Riviera,
Disneyland Hotel or FTW Cabins unless they are long term planners.