I agree. That's what I usually do. Unfortunately, the $90 change fee is an unnecessary cost of reward travel.

If there are spaces very close to what you want, grab them before they disappear. They are not necessarily booked/taken by other members, they may have been deliberately removed from the inventory by AC. 2 I seats on this flight for 3 days, then move that 2 availability to another flight for 5 days and at the end, it complies with the 8% requirement. So it's very much a moving target, so to speak.