“Just over a year” is approximately the minimum possible time for wanikani, since it enforces going through the levels one by one and most levels take a week if you always get all the reviews right as soon as they become available. I think it’s not a good benchmark. It’s trivial to hit if you cheat, moderately annoying but doable if you already know all the kanji, and so on, but for a serious learner starting from zero, “just over a year” is only an implementation detail that has little to do with how fast one is supposed to be going…
I think the best way to approach tools like wanikani or bunpro is determining an amount of time you’re comfortable with spending on them every day and then managing lessons and reviews so that you hit that. These tools only require you to show up every day and do as you’re told, so the most important part of using them well is making sure you actually want to do that for a long time.
Side note about wanikani and getting a firm base in vocabulary - keep in mind that there’s a lot of vocabulary that wanikani won’t teach because it’s not commonly written with kanji. Based on that alone wanikani levels are not a good way to measure progress toward a JLPT test…