BahrainLad
Thanks for explaining that!
Here's a thought though...
If narrow seat pitches speed evacuation by restricting flow into the aisles, thus preventing crowding and blockages at the doors. Then, if the doors are bigger you should be able to achieve a higher rate of flow towards them before you start to see blockages and the “faster is slower” phenomenon coming into play.
Consequently, with larger exits the benefits of narrower seat pitches may not manifest themselves. In, fact they could restrict the flow to below the optimum rate – i.e. the maximum throughput of the door.