Oh please. You pay most rental car balances at the end of the use so you can easily use the card then and not worry about cancelling travel.
If you don't shop for the best car rental rates, sure. The best rates are usually on non-refundable bookings. Again, we would be leaving some money on the table by paying more for refundable bookings just to use these rewards. Anyway, we almost never rent cars in the first place - most of our travel is abroad, and we have never rented a car in another country.
If you spread out say 1 night in a hotel across a few trips on this card throughout the year is the cancellation risk really that high? How many times have you cancelled trips in the past and had hotel costs reimbursed by your credit card company for it?
I only started using cards with annual fees and trip cancellation coverage last year. So far, I have not had to make use the trip cancellation coverage.
In the past, I used cash back cards with no annual fees, and purchased separate travel insurance. My incidence rate of actually using the coverage has been really high, maybe 30 - 40% . I have received 5 figures in non-refundable flights/hotel bookings.
The risk of putting one night in a hotel across a few trips is just losing the cost of that one night. Still not something I would rather do. I think what probably makes more sense is check out of the hotel using the card and pay for incidental fees such as dining, drinks, etc, and then use rewards to get reimbursed for them. We probably have enough of that sort of spending. I don't break it down between advance bookings and checkouts - just a "travel:lodging" category in Quicken, but I'm guessing this would be sufficient. I could likely get exact numbers by looking at dates of transactions nearing checkout date. Sometimes, we book full board though and there are no such checkout charges - happened on our most recent trip.