There is some disagreement among scholars about when and how the Donat was used. My own thinking is as remarked in 2.01, that some time was first spent in learning the alphabet and a few prayers, memorizing first and then “reading” in the sense of recognizing texts already familiar. A sharp student could get through this quickly, but some took a fair amount of time at it. When ready they would be set to memorizing the Donat, but all the discursive sources agree that these donatistae were still rank beginners.
“…the Italian Donat was originally a drilling book that went into considerable detail for students coming to the language for the first time.” In a practical sense would these students still have been Latin beginners, by the time they started the Italian Donat? Or would they have had some immersion in spoken Latin in the school, during the couple of years of preliminary training mentioned in the first paragraph of Section 2.01?
See now also Federica Ciccolella, Donati Graeci, Learning Greek in the Renaissance, Leiden, Brill, 2008, who gives a very thorough account of the Latin Donatus. On the Ianua, see especially pp. 20-46.
more difficult starting point] Yes, but we must approach these books as we might a Latin for Dummies that would provide all needed instruction for someone starting from zero. A part of analysis/evaluation of these books must be a reconstruction of the oral/aural instruction that preceded and accompanied their use.