I started with my Canton Ergo 1002DCs 8' apart, 20" off the front wall. The Left was about 5' from a sidewall with an upright piano against it. The right is about 20' from it's sidewall (actually closer to the left wall and piano) with other irregularities in the room including an unfinished basement "ceiling". My seat, a rolling chair, moves along a mid-line I've drawn on the concrete floor; between 8' (96") and 81" back from a line connecting the speaker faces. very slight toe-in. It sounded very good to me.
Then I got a CD that guides you in placing your speakers with voice and castanet sound effects. The results were surprising and made a huge difference in balancing the sound stage and other SQ facets. I won't go into all the details, because I doubt anyone is in a space like mine, but both my speakers are now toed towards the left wall and everything sounds fantastic. Shortly before I got the CD I had upgraded from a Denon DL-301 mkII to a Hana SL. Re-positioning the speakers a difference much, much larger than the new cartridge did! Best $20 I ever spent on my systems!