The only time I have spent more than 3 hours in an origin airport was when my flight was leaving around 5am. I got to the airport before midnight and stayed in the lounge overnight. There are also a few instances where I am connecting on separate tickets, so from airlines perspective, I am at “origin” airport. As long as time permits, I try to visit the city instead of staying in the lounge. There was one time I spent over 7 hours at YVR on a connection, because there was a snowstorm outside so I couldn’t go anywhere.