The the 13 month booking window is an explicit benefit of multiple week ownership. There are also implicit benefits to multiple week ownership. How important/useful these will be depends both upon the number of weeks one owns, how they utilize them, and subjective factors of ownerhship. Keep in mind that it behooves an MVC owner to learn both the rules of MVC as well as the rules of the MR program & the MR VISA and how you might turn collectively turn them into additional value. Multiple week ownership has several possible ways to do so.
All MVC owners are enrolled in the MR program and all receive annual MR Silver status which confers a 20% bonus when earning MR points either for a Marriott hotel/MVC stay along with 10 MR bonus nights credit for reaching MR Silver. The trick here is see the big picture of how to parley your ownership into additional value at Marriott hotels in conjunction with your TS usage.
Every MVC owner now receives MR credit for each night stayed at their home resort ( 1 week = 7 nights MR stay credit). Consider how a multiple week owner can benefit from this. A two week MVC owner could receive 14 nights credit plus the 10 bonus nights for a total of 24 nights of annual MR credit. A 3 week owner earns 31 nights, a 4 week owner 38 nights and so on. Just on MVC stays alone, the 3 week owner is 19 nights short of the 50 nights required for MR gold status ( which confers a 25% MR bonus, concierge lounge access at the hotels, room upgrade, and guaranteed room reservations ) and a 4 week owner is only 12 nights short of MR Gold status.
Why do I emphasize this? Because the wise MVC owner learns to combine their MVC ownership with Marriott hotel stays . . . sometimes you need to tack on a hotel night to a timeshare week or you simply do an occassional weekend trip someplace and stay at a Marriott property. A multiple week owner who plans carefully can parley their MVC ownerhship and non-TS travel into MR Gold status with the extra perks along the way. Mind you, this option requires some work and planning, but a good chunk of MVC owners are already traveling a lot and need only organize their travel better.
There are also some potential power players in this game. For example, those folks at Ocean Pointe who own multiple lock off weeks can turn 4 weeks of ownership into 8 weeks of occupancy utilizng the lockoff option. The kicker here is that they could earn 8 weeks x 7 nights = 56 nights credit in MR. This sort of owner can easily garner MR Gold status simply by tacking on the 10 night bonus received for being ( automatic ) MR Silver. MR Gold status requires 50 nights of stays.
We own multiple weeks and occupy enough of them which combined with our non-timeshare travel pushes us well into the MR gold level ( note: we ourselves do not lockoff our OP weeks & we earn straight up nights ). A huge perk here is the room UG and concierge access when we do a long weekend in London where breakfast normally costs $38 a person. We can eat in the concierge lounge for free, or do breakfast for an $8 supplment. It all derives form our MVC ownership and our dedicated non-TS travel plan by which we always stay at a Marriott property whenever we do a long weekend or other hotel stay.
Once again, it's not exactly a handout by Marriott, but it is a partnership with perks which improve as you become more deeply involved with MVC & you learn how all of the various programs intersect.