It works for me when I'm about an arm's length away from the monitor (though when I actually get the focus, I can move closer or further without losing it, though not too close lol). Works best when you don't assume distance though but move toward and away from monitor till you can see the effect. And what I did to actually see it, is to focus on one part of the image that stands out on both sides (same part on the left copy as on the right), and try to bring the 2 parts from both sides together into one somewhere in the middle, and focus on keeping it together. Then after about 2 seconds when I can keep the parts together, suddenly I no longer need to "try" or force my eyes to focus, it's like they adjust to that perspective and remain in it with absolutely no effort on my part. And I actually found that the most fascinating aspect of it - my eyes only needed to be forced to cross with conscious effort while seeking to find that correct perspective, but as soon as I find it and it becomes sharp, my eyes remain crossed all by themselves with absolutely no conscious effort on my part, like it's their natural perspective. Though as soon as I look away or something and lose that focus, eyes realise that they're crossed and just go back to "normal". And it's funny that once that "perspective" is found, my eyes refuse to unfocus from it - like they all on their own try to maintain it, and if I intentionally shift them away from that focus, they instantly find it again all on their own, like it's their natural state. But if I shift far enough, they dunno how to find it again by themselves so return to the real "normal" perspective.
And yeah, when they do return to "normal", I suddenly realize to my dismay, how boring and flat the normal perspective is lol. Hope that helps!
