Once you’re in the 現実 levels, WK becomes an exhausting sprint anyway, with every level having become a fast level. I can’t imagine wanting to pile more kanji study on top of that.
Much more than what we learn here would be overkill. Take 箋 for example - the modern Japanese language has exactly 2 non-archaic words that still use it, and in both cases, this kanji is usually written in hiragana.
No need to anyway, it’s easy to memorize. Take a look. Make up a memory aid. Now it’s yours, but you’ll likely not see it anywhere ever again, at least not if you just live a normal life in Japan and don’t read obscure ancient texts or crazy visual novels that try to come across sophisticated.
Interestingly, I learned that one in the wild from frequent exposure to 処方箋 
The hospital I was going to was using the full kanji version on their prescription. I guess they were feeling fancy. After going there on a regular basis for 6 months, I was pretty much set for life.
But, yeah, obviously there’s no need to study that kanji, for the exact same reason. Honestly, there’s no need to even go beyond level 50 on WK, if you think about it. It’s just nice to have the option.
My main reason to go with the beyond WK deck is that there are many kanji “in between”, that I see often, but not often enough to remember. For instance, one of the last book I read had the word 歩哨 (sentry). I bumped into that word again recently, but had forgotten the reading. So I was happy to get 哨 in that deck. Same goes for 鷲 叢 and 趙. Obviously, I could eventually learn them through exposure alone, but the fact they are infrequent makes that natural process harder. YMMV 
Have you learned any kanji from WaniKani that you didn’t know at all? Or just ones that you kind of knew and solidified?
It’s a bit of a diminishing returns problem. At some point, just reading does more for you than studying flashcards. My personal goal is to rush through one of the core decks on iknow later (to pick up words I missed and solidify kanji I’m still shaky at), and yeah I think lvl 50 should be more than enough for that.
Personally, I’ve only ever seen 処方せん here, I must have missed all the fancy hospitals 
Then again, I’m a simple man, hehe.
Depends of what you mean by kanji I didn’t know at all. There were kanji that I had seen before, but I was unable to produce either a meaning nor a reading. A recent one was 墟. At first I went ???, but once I saw the associated vocab word 廃墟 I suddenly remembered where I had seen it before. But yeah, in isolation, that was completely blank for me. However, there hasn’t been a kanji that made me feel like “nope, never seen that in my life”
It’s mostly consolidation, though. There are about 3-4 kanji at each level for which I could not remember the meaning or the reading. (I think level 31 had 10 such kanjis; I wasn’t very happy about it at the time)
I agree, but it goes both ways. There’s just so much reading can do for you. At some point, reading more won’t give you much improvement. Especially since I’m reading a bit all over the place in terms of style/content.
Moving from there, I guess I should have started writing instead, to fixate stuff more, but instead went back to SRS…
The curse of Level 31, huh?