Depending on your definition of Requires and of Check In, Air Canada says:
In the "When you should check in" for flights "From Algiers (Algeria), Casablanca (Morocco) and Tel Aviv (Israel)" - 180 minutes. It's true that checkin only closes 1 hour before the flight leaves, but if everyone showed up 1 hour before the flight left, some of them would not get checked in. Does "should" mean "requires"? You tell me.
Further, the same page says (twice!) that when flying "To the U.S. From Toronto Pearson",
For departures before 10 am, wait times are longer than usual at U.S. Customs and Border Protection (CBP) and Canadian Air Transport Security Association (CATSA) pre-board screening. You should arrive at the airport three (3) hours before your flight's scheduled departure time. Pre-board security screening for departures to the U.S. opens at 4:00 AM.
I routinely arrive at Pearson 3 hours before my flight leaves. Yes, I usually then spend about an hour at the gate area, mostly because I have Nexus and thus get the express security lanes and a quicker experience if I'm preclearing to the US. But sometimes it's a little less than an hour. I don't find 3 hours an unusual recommendation.