I suspect it is a bit more complex than just "the latest". As I see it, you can purchase the "Preview plans" and Build Manual, but these are just an example, and may be outdated.
When your kit arrives, it has the latest Build Manual pages and Plans for that kit of parts. These should then be used together, and not get (individually) updated... i.e. the parts, Build Manual and Plans go hand in hand. Were you to get a new "plan" in isolation, it might refer to updated supplied parts you do not have.
An example was the RV-8 kit alteration a few years back. The plans and parts changed markedly, and were you to mix and match, you would have had endless problems
