My friend learned japanese in a very unconventional way, is it perhaps effective or rather ineffective

Hi yall, so my friend started learning japanese a few years back and actually became quite good at it and the way he learned it, is kinda weird and i wonder what yall think, so he basically learned the language seperate from the script (so in romanji) like he learned the grammar, a lot of words, etc. And then after that he started learning kanji but he didnt learn the kanji seperately but firstly learned the base radicals that appear in the kanji and then just learned vocabulary items and the kanji they use to get like a feel in what compounds what pronunciation of that kanji is used. According to him atleast. This seems very different to how most learn japanese so i wanted to ask yall whether you guys think whether this method may be effective? Cus i may start learning it a bit myself because of a friend.