So here’s the thing. Benny has essentially rediscovered by himself what the Foreign Services Institute has said all along: European languages that are related to English are easiest to learn.
I believe because he has had some success using his method he has under-estimated the effort required to learn the “harder” languages.
That said. Benny’s method is much more efficient than the FSI’s old school method. They reckon it takes 500 hours to learn an easy language like french and 1,500 or so to learn a harder one. I think it is possible to achieve “fluency” in a level 1 language in 3 months using Benny’s method no problem if you put in about 3 hours per day of hard exposure to the language. That’s still about half the hours required according to the FSI’s old school method.

Also I’m not sure that C1 is necessary to be “fluent”. High B1/low B2 will cut it in almost every situation unless being a “professional” or a university student in the target language in question is the goal.

My gut feel is that it’s possible to get to B1 in an asian language spoken/listening in about 6-9 months by using Benny’s method. Reading and Writing are something else entirely.

Yeah, that’s just crazy talk on Benny’s part. A lot of French words are just English words pronounced with a French accent because a lot of English words started out as French words. Same to a lesser degree with German. Not true at all of Chinese.

He also redefines fluency as not including any topic he wouldn’t want to talk about in English, so no politics or world events.