The person who can leave early has a different relationship with the meeting’s delay.

Delay is not the same experience for everyone in the room. The person with a train to catch, a child to collect, medication to take or a body that cannot sit comfortably past a certain hour is paying a real price while the discussion drifts, and the person who can stay all evening rarely feels it. Nobody announces this. It gets absorbed quietly, and the same people absorb it every time.

If you run anything, end when you said you would and treat that as a matter of fairness. If you cannot stay, say so at the start rather than slipping out apologetically.