Some speakers are more demanding than others.
I recall setting up some Spica Angelus - they were capable of pin point localization but needed to be positioned exactly right to get that. Helps to have someone to help you - if you can just sit there while the helper moves the speakers closer or further apart, or toes them a bit, it is easier to compare the sound in your own mind.
My current main speakers (Wilson Maxx 2) have advantages and disadvantages. Each one weighs over 400 lbs so you have them on casters to even be able to move them. We used a laser range finder to be sure of distances to listener and moved them back and forth to zero them in. They have the advantage of having the mid and treble drivers in a movable module that you can precisely angle according to head height and distance from speaker. Still, it takes awhile to set them up.
Right now I am doing battle with a pair of original Martin Logan CLS - slight changes in distance apart and toe can make or collapse the soundstage, plus there is the variable of amount of tilt, and height off the floor (customs stands are either unsightly or impossible to find).
It is worth all the trouble once you get the zeroed in, though.
