This doesn't hurt to do. But IME, rarely works. It really depends on the type of room you book. As a Diamond, I've had to change rooms (but the rooms were significantly different). Apparently I would not have been upgraded to the really nice room because others had booked & paid for it (like I had for the first night). With the same room type, no need to call ahead. Letting them know at the the first check-in is enough.

I've always had to "check-in" between reservations even though my key had supposedly been "activated for the whole stay. Bad way to find out it was not true when locked out at 11pm and on the 12th floor.