I think DD would say that they should be a shorter series of larger books, rather than such a long series of short little ones or one big one. She seemed to think that there were bunches of the MT books that would have been better if they were published as 1 book with more chapters. But, since the general format is the same throughout each little adventure, she didn't think they should all be together because she felt it would get too repetitive.
She has always been someone who likes thick meaty books over thin little ones.
Of course, this is for the girl who would read 24 hours a day if we let her!
Good luck with your book!