Should MCT be flight-dependent?
From what I've seen at AA LGA, they will hold the last flight and wait for incoming connections.
MCT is different for codeshare vs operating airline. I've seen MCT for DL to DL (operated by KL/AF) at LHR significantly shorter than DL to KL/AF. Same exact flights. As a result you can buy revenue ATL-LHR-AMS under DL code but can't redeem award for same flights as LHR-AMS has to be booked as KL.
Saw something similar for DUS-RSW-CLT. If booked as AA codeshare not a problem but can't book as AB-US.