When your speakers are 6-8 feet apart..The stereo image is fine in just about any room..Naturally there is a sweet spot, and when I set up ..the sweet spot is where I stand..
When speakers are this distance, the audience can still get the stereo image as with a real band..They will hear everything.

In certain situations , as when speakers are 20 plus feet apart, because of a wide room...mono may be the better choice..People far left and far right would definitely have an unbalanced hearing of the music..