It's quite a bit more complicated than "decorating a few rooms." Any prospective design needs to be deemed appropriate for the entire resort before it's even put into place. No sense in decorating a couple model rooms, only to discover that the design is too expensive, not durable enough or that they cannot even obtain materials in sufficient quantity to renovate nearly 500 villas.
Before any model rooms are prepared, there's a lot of behind the scenes work to be coordinated between designers, contractors, suppliers and even resort management to ensure that the design is workable for a high occupancy timeshare.