Keep a place for the person who is slower to enter a conversation.

Group conversation rewards speed rather than value. Whoever thinks by talking gets in first, the topic moves on, and the person still assembling a sentence learns to keep it. Over a few months that becomes a room where the quickest views are the only ones anyone hears. Nobody chose this, and everybody loses something by it.

When a subject is about to close, ask the person who has not spoken what they think, and then wait through the pause without filling it. Three seconds of silence is usually enough. If someone gets talked over, hand the floor back to them by name.