None of the airlines factor in the gate arrival and boarding time requirements in their MCTs or scheduled connections. The reality is that no one is actually checking if you are at the gate 30 minutes prior to departure and they generally don't close up the flight right at the 15 minute mark if there are late arriving pax from other flights. That said, I've had a couple cases where they have cleared standbys and closed a flight slightly early and I lost my seat when they didn't think I could make it from my connecting flight.