The point I want to make is that most people underestimate the effort required to learn Japanese, and overestimate the fun it will be. Those “learn any language in 3 months” quacks are not really helping there.
Looking at how many people start WK and how many finish, I think the number of people who move on to greener pastures, breeze through all the kanji in 3 months and look back laughing how everyone tried to hold them back can be counted with a small number of fingers. Giving up because Japanese is not worth their effort is the more likely answer.
The argument that something is “more effective” in terms of time does not really convince me. Keeping the motivation is the problem, not if you need 3 months, 6 months, or a year to achieve your goal (and a small step in learning Japanese).