Middle Ground?

I got my rosemary shredded today and most of the honeysuckle dug out.
Had to do it in a small hail shower though.
What is it with the weather?

Tonight at the camera club we had a studio session.
The 'instructor' was talking crap about a lot of stuff (like - you will not get a good picture tonight .... you never do at club nights) so I slipped out and set up another set of lights.

I got some nice shots of all three models we had.

Other members came in and found all their shots were coming out overexposed at first ......... turned out "he" had them all using 400 iso because "anything below that gaives flat and uninteresting shots".

Anybody want to explain that one to me?
I have no idea where that idea comes from.
Not something I have ever heard a pro come out with before