OK. It took a lot of reading and my maths are not great.
I found the sections VII and VIII where they did verify that it was a real effect.
I am still not sure about the values they used for friction and turning effort on pedestrians.

I don't read Russian so I assume the summary is "Put some kind of obstacle somewhere on one side of an exit if you need to move a lot of people through it."

So what kind of effect would placing the exit near a corner of the room or close to a wall have?

I have copied and I will read again.
I am not sure if I can use it but it is interesting.