Tewi: I'm sure most people visualize with their eyes closed, and we do too, but the topic's actually slightly more interesting for us than that. For whatever reason, our visual clarity actually improves when we keep our eyes open while doing it.
However, we do still visualize with our eyes closed because it's easier to focus like that. Keeping our eyes open is at least a little distracting for us, not as immersive. But it's really bizarre how our visual clarity just improves by like 10% instantly by doing it with our eyes open - I wonder if anyone else experiences that? And, of course, some people just prefer that by default.
* Side note, if this all sounded like nonsense to you, you may want to google "Aphantasia" (edited)