This is wording from Amex that we have seen, albeit the information is from a number of years back:

"In no event shall coverage be provided when the Cardmember rents a Rental Auto beyond 30 consecutive days from the same Rental Company, regardless of whether the original agreement is extended, or a new written agreement is entered into, or a new vehicle is rented. Additionally, no coverage will be provided when the Primary Renter rents a Rental Auto for more than 30 consecutive days out of a 45-day period within the same geographic market/location (75-mile radius).”