I find that in the case of a Nikon SE 12x50, eyecups touch my skin around my eyes. That causes a little stress on the eye, a focusing difference. Maybe it is just my face. I see the entire FOV better when the eyecups are folded away from me. I need to trim the eyecups to make them perfect on several of my binoculars. The most prominent example is the Oberwerk 11x56. It seems to have 3 mm too long eyecups and prevents me from seeing the field of view all the way to the field stop. I am impressed that you have noticed this detail, EdZ. You seem to take everything into account!