How far apart do you position your speakers ?

I did the plane of the speaker to the ear, but I believe the 83% mentioned in this thread was from ear to speaker.
The way I did it worked well for me. I have my rack on the side wall, so moving speakers farther apart would have meant closer to the gear.

I find that a listening distance of 1.5 times the spacing between speakers works best.

If you listen at 6 feet then speakers spaced 4 feet, at 9 feet spaced 6 feet apart, and at 12 feet spaced 8 feet.

I find the often recommended equilateral triangle with toe in does not sound as realistic.

I prefer speakers facing forwards and square to the room - no toe in or toe out.

I do not respect speakers that change their sound character with angle.

I will only use speakers with even dispersion across the main frequency range.

As far as they need to be.

Not all loudspeakers are designed for facing forwards most are designed with toe in in mind. The reason is the frequency response on and off axis. There is no rule that could ever tell me where to place a loudspeaker or how far apart. To many variables. So best to set them up to sound best to the owner weather placements right or wrong is subjective and even ones height or chair height, room decor, seating distance ,room and speaker size, speakers radiation pasterns etc. all can effect placement. No one way for all loudspeakers and the formulas to me are all far to over simplified and biased to have any real use.

I think Johnk just said it all. There are plenty of formula's, get one to work