Our usual connection at IAH is 1h 12m and believe me, we've had to run at times, and yes, we've missed some connections, too. Remember if your inbound flight is just 10 mins late, you still have to get off, check for gate changes (get your airline's app on your phone) and get to the gate. That can be a challenge even knowing the airport very well. And again you may be lucky and come in very close to your next gate or like we had happen once, actually get back on the same plane for your next flight. I'm like many frequent flyers that I know and really don't want the hassle of tight connections and usually book flights with layovers of about 2 hours or so. I appreciate this more as I get a bit older.