No, this is a very new thing on SLR. If you go back about 5 months you see the first split/multipart JAV video starting (Rima). Before that virtually every JAV title is one video, regardless of length, like every other genre. It was never like this before.
https://www.sexlikereal.com/tags/jav-vr?from=autocomplete&sort=most_recent&page=13
And who cares about length with streaming and bookmarks? It's easier to jump around in one long video than switching between 2-5 separate titles. It clogs up the chronological view and favorites lists. You also can't see the Part #'s in the thumbnail view to view in order. Splitting videos is terrible UX.
JAV producers may have offered split and whole options in the past. But SLR was choosing the single title until exactly 5 months ago (or recombining them).
Please go back to the single title format.