I'm following you just fine, thank you. I tried all the possible permutations of those settings before I made the original post. I am a very experienced Kobo user, going back to the very first Kobo in 2010, and I'm a Kobo beta-tester.
After many hours of reading, the ridiculously short values listed for time remaining persist in every place where they can be shown (home screen, My Books, footer, reading-progress graph); the values are consistent in all places. (
Percentage read counts and the bottom-of-the-reading-screen progress bar are accurate, however.)
Showing "2 minutes to go"
in the entire book (not the current chapter; the entire book) on a book that has over 20,000 words of text left to be read in it is not a case of the device learning my reading speed; it's a bug or some sort of corruption. I'm fast, but not that fast.
As I said, I've been through all settings (all of them, every menu, including toggling including end matter in the calculations on and off), as well as all the values in the "Kobo reader.conf" file.