This isn't a very good guide, since it doesn't even take egg sizes into account. As a fan of egg, these timings are completely wrong for Large Lion Grade A eggs.
Also anyone living above sea level would have severely undercooked eggs. I live almost a mile up and pasta takes two minutes longer to cook so i assume eggs do too.
Yes! Very good point. I used to use an app for my location, which would adjust the timing based on my elevation from sea level - even though it's not much where I am, the adjustments certainly made a difference!
I would link it but it is now riddled with ads, and has a generic name of 'egg timer' ._.