Setting the side mirrors at 90 degree

I wrote to my friends:

"Can someone please tell me if this setting the side mirrors of the car at 90 degree is a good advice or not???  As per attached powerpoint"


Stephen's advise:

"I believe a shoulder check is the safest practice of all in the case of lane-change. Otherwise, I don't think it matters much."


LP's advise:

"Never heard of it and still don't understand it even from looking at the slides twice.

BTW, if someone sends you an attachment such as word doc or powerpoint - don't open it if you don't want to catch a computer virus or something.  So it is best if you don't forward it either.

All images / slides should be viewed from some website."


Sam's advise:

"This is similar to the way I set my mirrors.  I think it is good idea."


The morale of the story: DEPENDS...