Many people buy in to save money - which you don't do by staying in one bedrooms. So we generally assume people are trying to book studios unless they state differently. One bedrooms aren't terribly popular because they are a lot more points for the same number of people as a studio (they are a wonderful value add though). Two bedrooms become popular again for larger groups or people who want to spread out. And Grand Villas are popular for big family trips, and there used to be not many of them, so they'd book fast. We've added a lot of GVs to the system between SSR (plus treehouses) and VAKL - it used to be just OKW and BWV that had them, and BWV only has seven - so availability is less tight on those as well.
People who buy only enough points to book studios, then expect to be able to get into BWV/BCV/VGC/VGF at seven months whenever they want it are probably in for disappointment. All those resorts will be available at seven months for studios sometimes, but none of them will be always available. And you'll have to get lucky to book them if you wait much past seven months year round.