When we analysed the reasons for the causes of delays it was found that the two main causes were passengers doing last minute shopping and exec club members leaving the lounge late
Let me tell you about an occasion en-route back from the Middle East to Brussels through Terminal 4. The Brussels flight was delayed, and I was waiting in the Lounge. Eventually a new departure time was posted. This was in the days when the Lounge staff made a boarding announcement, but I was keeping a
very close eye on the screens. Twenty minutes before the revised departure, there was still nothing on the screens, but I decided to move to the Gate anyway. I checked with the Lounge reception, and was told that no, it was not boarding yet. Just as I moved away from the desk, the screen changed to 'Boarding Now', and I heard the first Lounge announcement as I walked away towards the gate. I arrived at the gate 15 minuted before the revised departure to find the doors closed. "No I could not board, and my bags had been offloaded". They did put me on the next flight, but that was a further delay I could have done without!
So be careful about blaming passengers for leaving the lounge late.