Good to have this discussion and all the responses. A few responders have mentioned that they do not have dedicated rooms, with a bit of lament. A dedicated room is not necessary, but dedicated music listening is. In other words you need to just listen to the music and not do anything else. As I have mentioned a couple times, for background listening, nothing really matters in the speaker positioning.
If you are set up in a multipurpose room, it's best to not move the furnishings around. Everything in the room affects the sound. And if you move things around you need to adjust the a speaker setting to get back to the optimum sound. The Sumiko/Master Set method that I referenced in my first post is said to work with any speaker in any room. And thus it can be tried in a multipurpose room, some times quite successfully
As to "Optimum Sound", there is likely a few definitions of that and with a lot of divergence. I will only say that optimum sound is the perfect summation of the two speakers to be as if they were one speaker.
A good way to check for that is to listen to a mono recording, and mono recording will do. By definition there is equal music in each channel and each speaker. The two speakers will automatically sum together to give sound perfectly between the speakers, no matter where you sit in the room. If you do this with your speaker set and go to one side and the sound also goes to that side then you are getting more sound from the speaker on that side. That should not be and you do not have the speakers set for optimum sound. This is a good check because the mono recording can be a reference as to what you are trying to do with the speakers.