Are Foldouts Always Shorter to Left but Longer to Right?

[ReneZ]

There are still unanswered questions. The early mix-up between herbal A and herbal B folios happened before the gathering marks were added. This is because, for example, the 5th quire mark is on a B folio.
There are several different possible explanations for this.

Hi René,

I’m not sure about what do you mean by mix-up between Herbal A and Herbal B. For me, there are two understandings.

Hello Zhe,

indeed, mix-up is not a very clear expression. I meant that B-language bifolios start to become interleaved among the A-language folios. The start of the book only has A language.
These pages are different in three respects:
- different handwriting (Currier hand)
- different text statistics (Currier language)
- much more verbose (more lines, and more characters per line - both on average)

Either this was the intended order of the book, or it became disorganised at some point in time. The fact that there are additional herbal pages towards the end of the book could be one of several signs that the page order was disturbed.

For the person writing the quire numbers there are also two possibilities: either he knew what should be the right order, or he did not. 

The folio numbers could have been added at a much later time, even late 16th century.
However, there is no easy way how everything can be explained.