The author definitely benefits from French and English being related languages. Remembering that "interesting" is "intéressant" takes a lot less effort than remembering it is "おもしろい".

I studied Japanese full time for a year and would probably average something like 20 word a day but even that was pushing it. I advise people to aim for 3-5 words a day and be consistent. Adding huge amounts of words very quickly and then giving up on reviewing them is all too common.