Looks like most people do what I already do. Yes I usually backtrack the flights and check the incoming flight and it’s schedule. The only possibility that I cannot account for is if they use a different plane. I rarely arrive to the airport for the original departure time if it’s delayed especially if I’m coming from home. I can’t see myself waiting at the airport for 3 hours. I departed from SMF so it’s not a hub for anything. The plane ended up leaving at the delayed time and I made it to the destination.