Speaker distance

It seems to me that the ideal distance between the speakers varies from one recording to another depending on the mix and the instrumentation. I notice with solo piano and with string quartets that no one setup satisfies every recording. So I try to find a position that works most of the time. Maybe we need moving sidewalks with remote controls that would allow us to easily place the speakers close together for say, a solo guitar and far apart for an orchestra or big band.  

I agree. My listening chair is on wheels and I can easily move a little forwards/backwards (whilst seated) to achieve the best position. 

Dedicated room: use the 1/3 methodology, 1/3 length of room for distance of speaker to back wall; 1/3 length of room for distance of chair to wall. Then I used cardas calculations for distance from side walls. Fine tune toe in.
room tuning devices applied as well as bass traps in corners 

Audiophile nearfield desktop....  about 38 inches apart.   Audience 1+1V2's. What I hear does not sound small...  Just to scale. 

Spendor sp100s, 6 feet apart, my ears around 3 feet in front, strong toe in so I can just see the inside plane of the speakers. The Spendor’s are way out in the room, with about 8 feet behind them to the back wall. REL G1 sub in the right back corner. I have been listening near field like this for the past 15 years, and it’s great. On good recordings, they disappear and project sound all around me, even behind me. 

Geoffkait, is the signal both in and out of phase pink noise? Where can I buy this test disc? I am using multichannel 5.1 and have 4 ceiling speakers for Atmos. My preamp has a room correction software built in and has a test where you can see the plots pre and post and can move the speakers in real time. I wish there was a way to find the best location in home theater usage. I have always thought of remote controlled speaker bases that can move the speakers while you sit in your listening position. Also it could be integrated with the room correction so the software could move the speakers while sending the test signal. I am using Anthem AVM 60 and the correction is called ARC. I agree with your idea that there is only one correct position just wish it could get done by the equipment with built in software. Very interesting DIY room treatments on You Tube.