From my experience with YYZ, they won’t start boarding the next flight until around the time you’re scheduled to land (or at least not until after the plane was supposed to leave), and they WON’T declare a delay or tell anyone waiting at the gates what is going on.
Oh and don’t ask the customs people any questions or they might try to find a way to punish you. They refused to tell us that we were waiting fifteen minutes in customs because they failed to warm up the machine before telling people to get in line for that machine.
Never again YYZ. I thought America had bad airports…