We buy the $199 travel insurance every year. We own a number of Marriott timeshares (over 10) and it covers all of them as well as our Vacation Club Point (VCP) reservations (a low cost per reservation). I think we have to be on the trip for the insurance to apply - read the policy.
Week ownership reservations - We have had a few claims over the years usually for reservation cancellations due to illness. The claims have usually been to recover our maintenance fees at 100%. We have usually been able to cancel hotel reservations and airline tickets for either a refund or a credit toward future use, so no insurance recovery. I think claims coverage would be limited to your out of pocket after other insurance coverage. I suspect trip delay, trip interruption, missed connection, baggage delay or loss, car rental collision, accidental death and dismemberment, emergency evacuation and repatriation, might be infrequent uses. I like the accident and sickness medical expense limit of $25,000 as I think it covers 7 guests (especially useful for active grandchildren).
Vacation Club Point reservations - Because you can cancel up to the travel date, I doubt that the trip cancellation due to illness is of much use as you would get the points back (so no maintenance fee claim).
Another thought - We buy the insurance every year in about May for the next calendar year. Remember, the coverage addresses the year of the reservation, not it's use year. So, continuous every year coverage ensures coverage for carryover weeks, points, etc.
Hope this helps.
PS - The travel insurance might be useful for cruises acquired through use of Vacation Club Points.