Something not often considered is that cross-eyed stereograms allow for both better focus and (if desired by the artist) also stronger depth when someone is vie

Something not often considered is that cross-eyed stereograms allow for both better focus and (if desired by the artist) also stronger depth when someone is viewing the image without hardware assistance. The two unassisted viewing options for the majority of people are either crossing your eyes or looking through the image to infinity. Intentional exotropia is completely off the table, because almost nobody can do that (because there's no natural point to doing it, unlike crossing which is how you look at things near your face). And the problems with looking through the image to infinity are that 1) If the image is near you, you're now naturally focusing far away, which means you're not focusing up close on the image plane like you would be if your eyes were crossing, so the image is blurry without an unnatural muscle behavior. 2) If the image is meaningfully far away, the angular difference you can achieve between it and a horizon vanishing point is just too small to achieve overlap between the halves unless the image itself is very small, which you then won't be able to see anyway.