For those thinking it is jut the OS taking up all that space, it is also what they allocate in reserve for games to use. For example, quick resume uses some of this reserved space which is pre-allocated on the SSD for this. That is why some reviews were able to have more games in quick resume than others. For example, if you were to "only" play OG Xbox games you would have a ton more games you can have in quick resume versus having Xbox One games in Quick resume. What they seem to be doing is giving a specific amount of space on the SSD for this function. If a games quick resume save state takes more space, then that leaves less space for other games...hence why some previews were able to have more games in quick resume that other previews.