Right. It's not that most channels have good hand-edited subtitles; it's that it's not too hard to find channels that have them. Usually once you find an interesting video with subtitles, most the rest of the ones on that channel will also have them, so that can easily be tens or hundreds of hours of subtitled content to work with.
It gets even easier if you set up a separate account that's dedicated to your target language so the algorithm's not just feeding you endless content in your primary language.
To this day I can't understand Youtube's asinine decision to not let me deactivate autotranslation of titles and the fact that it isn't consistently triggered makes it so much worse
It gets even easier if you set up a separate account that's dedicated to your target language so the algorithm's not just feeding you endless content in your primary language.