Beyond that, though, there are some considerations. One can "read" an Audible book while walking or dusting or chopping vegetables, but one cannot read an Audible book before bed. I've tried that before, have fallen asleep to a mellifluous voice carrying me sweetly from novel to dreamland only to find myself hopelessly lost and frantically rewinding (using that five-seconds-back key) in the clear light of day.
With eyes on paper, though, the worst that can happen is that you lose your bookmark in the bedcovers. But that, and one's place in the story, is easily found the next morning.
So there develops the two-channeled reading mind, which thrills to American Dirt in the evening and revels in The Heart's Invisible Furies in the morning. And why should it not? After all, it's the same mind that holds recipes and birthdays, addresses and passwords. It can juggle more than one movie or television show in an evening, so why not two books in a day?
I say this now, of course, but I'm only a few days into reading double. We'll see later how it all turns out.