I think the right learning method varies between learners, as I read of different people having success with different methods. It would be trite to say that the right method is the one that works (for you) but that is what it amounts to. if someone tries the Koch method and finds it is not working for them, they need to try alternatives.
I don’t like the Koch method myself. I think it builds memory pathways that are undesirable. Eg I find people mixing up G and U and it makes me think they learned by a method that involved remembering combinations of elements (dots and dashes) and those combinations remain associated with each other, whereas learning the sounds and going directly from sound to letters is more effective in my experience.
It needs to be treated as seriously as one would treat learing a language. You are training your brain to do something it has not done before, or for those who have tried before, unsuccessfully, they are having to unlearn some complex (long) pathways and relearn correct ones. There is a video in which the letters are shown on scrren as dots and dashes. My advice is never look at it. That is telling your brain to translate from a sound into dots and dashes, then convert that to letters.
And just as you are tested when learning a language the learning method needs to test and retest the student’s memory. Whereas listening to it and saying you know the entire alphabet does not test you.
I won’t go on. Hopefully this is enough to illustrate what I meant.
73 Andrew VK1DA/VK2UH