IMHO there is a “sweetest spot” with only room for one. But that doesn’t mean that there isn’t a larger, good sweet spot.

One of the main reasons for a center channel is to anchor center material in the center even if one is not sitting exactly half way between what would have formerly been a stereo setup. So in a 5.1, 6.1, or 7.1 situation that centered effect is not lost from any position.

In a movie theater, the surrounds are usually mounted quite high. That way there is less neighbor-to-neighbor trouble with the sound and no one is seated immediately adjacent to a surround speaker.

To some degree, the same principles used in a movie theater can also be used at home.

For listening at home or in a theater, I still prefer the center third of the room left-to-right, and the center half front-to-back. That leaves me with a sweet spot that is about one-sixth of the room.