Cubigbird is correct, except for the fact that only 50% of phase 1, buildings one through nine, was available to non-event week owners. 100 % of buildings 10 on were sold as event weeks. I’m not sure of the exact amount, but there are roughly 270 2 bedroom L/Os in buildings one through nine with 50% already reserved as event weeks. That leaves approximately 135 2 bedroom L/Os available for tens of thousands of owners. Additionally, any weeks that were not sold were put by Vistana into Adventouras.
It is possible to occasionally snag a random unit, usually a studio at the eight month window because sometimes a fixed week owner will trade in a unit. This year, I did not use the studio side of my week 51 and could not find a renter so I was forced to trade it in before the 60 day window expired.