You ever play the game with W called "honey, let's move the furniture"?
It is a fun game. My mom was nuts with the game when I was a teen. I told the W that she could hire some movers if she ever wants to play the game.
Well, speaker placement is just like "honey, let's move the furniture".
There are no good rules for placement. Anything should be tried at least twice. Maybe three times just to make sure you didn't really like it the first two times. And if a rule is written, it must be broken.
And then the next week, some idiot (my name for the W), rearranges the books on the far left bookshelf, and I have to rearrange my entire HT just because she thought my collection of James Michener hardcovers shouldn't be displayed on the top shelf.
Ok, end of my tirade.
Now you understand how difficult speaker placement can be.
My suggestion .... play with the position, sometimes just an inch of movement can be a significant improvement.
By the way, I have my sub located freestanding in the "middle of the room" (it is actually 2' from the wall), and I am currently tweeking (rotating) the sub in 5degree increments. I may never get the right position.