Try to forget Pages
An EPUB is more like a roll of TP
that you unroll as much as needed to fill the screen (1 sheet per current zoom).
Splitting at Chapters also helps with performance on low power devices. I split even for a tiny chapter, just for
structural consistency
A side benefit of working on a single chapter: screw-ups
leave less to fix
You can Merge (consolidate) those fragments of chapters. Select the pice to be added above: ctrl-M (Bulk mode: Select the whole set of pieces, incl first piece, ctrl-M)
I have seen single books with 170+ chapters (EPUB about 1M). I recently saw a
Boxed set (22 books) done as 1 EPUB (9M
)