I’m also someone who came to WK as an N1 holder. If you want to know about the details, here’s my full story.
The tl;dr is that I have done something similar to your approach (albeit with anki rather than WK). It’s good enough to get to the point where you can read native content and pass the N1 test (well, assuming you study the other elements of Japanese as well, of course).
However, leeches and shaky memory will happen, and native content will do nothing for you. Here’s a recent example:
I came across the word 倹しい, which means frugal. There was no furigana but I knew the meaning, so I could keep reading just fine. I hazarded a guess at the reading, and went for 険しい (I’m not putting the reading here on purpose, so that people do not randomly get wrong stuff in their mind). Look! The okurigana fit! It must be right! Except it’s not. Good thing I checked, otherwise I would have had a wrong reading reinforced in my mind. And, of course, I also know what 険しい means, which adds insult to injury.
So, no, just going for native content isn’t the solution either. I wish it was, though, because it’s much more fun than studying.
With all that being said, I don’t think there’s anything wrong with your method, and it’s basically what I have done the first time around. I didn’t use the ignore button on WK, but that’s because this time around my goal is different. I wish there was something similar to WK in a Japanese only version, but I couldn’t find anything.