Of course they can book weeks within a season; that’s so obvious, I’m not even sure why you bothered writing that. The specific week within a season makes all the rental and usage difference, but you pretend it's not a big deal.
Regarding how they book their own inventory, you have to look at the facts and use common sense. In 2023, they reported $570 million in rental revenue, excluding sales packages. At an average of say $250 per night (you have to include low season and smaller units), they may need to book around 2.3 million nights per year. They also have about 200,000 sales tours, and assuming four nights per package, that adds about 800,000 nights. While I do not have the exact number, it is in the millions.
Do you genuinely believe someone stays up at night to book millions of nights every year using the same tools as you and me? Do you really think they don’t set aside inventory for their own rental business? You seem to be well connected with Marriott, so why don’t you ask them? As for me, I do not claim I know how they do it but I find it extremely unlikely that they book such a large inventory the same way as the regular owners.
By the way, I’m pretty sure that even if they use some automated processes to book or set aside most of their inventory (and again, I don’t claim to know that for a fact), they would still need a significant number of people to review those bookings and make constant adjustments for each resort. I’d be curious to know if those employees are paid by the corporate office or by the resorts for an activity that would only benefit Marriott. If it’s the latter, the practice must change and they need to reimburse the resorts for the time spent by those employees managing Marriott’s inventory.