I strongly oppose to this approach.
Catching up a full version demands a lot of effort and delays the availability of the Guides much after the release of the software.
We had a lot of work to bring our documentation from release 4.x to 5.x and now 7.x . We had to skip some releases because we could not match the release pace.
Small updates and frequent publication (6 months) is, as you see, much easier to track and provide a good doc for end users. Many chapter just don't need changes and can be fully reused. Other chapters need in-depth reviews.
Imagine purchasing the latest proprietary software and get a 2y-old manual in a promise that "will soon be available". Of course LibreOffice is not a proprietary software and documentation is produced by volunteers that have their own tempo.
Software with no documentation is a lesser software. Doc and software are components of a product offering.
Producing a new book with small updates is easier, quicker and may not require a full cycle review.
My 2 cents