It’s my personal judgement based on having used both systems 10+ years apart. I did RTK years ago before & during a couple years I lived in Japan. I chose WK to get back into Japanese while filling in gaps in my knowledge.
So I will give a long answer. You are graciously engaging people in your thread, so my apologies that you already know a lot of what I’m about to write!
RTK works brilliantly at doing just one thing. Using it teaches you only the meaning of 2000+ kanji. (Really you’re teaching yourself because after a few hundred levels you’re making your own mnemonics for each kanji.) It was the most elegant, complete solution to the biggest problem in learning Japanese. All the later systems (like WK, Kanji Learner’s Course) build on its achievement.
But RTK depends on two things:
- (1) It asks you to create mnemonics of your own;
- (2) it puts the radicals and kanji in a very specific ORDER. Here’s a good example. RTK teaches 凹 and 凸 right away (both level 57 in WK). They are easily-learned kanij that show how kanji work as a system. They are visual, they show stroke order, and they are component graphemes (radicals) that build other kanji that come later. You really can’t skip around.
Of coures, WK uses radicals and mnemonic stories too. Its order frequently overlaps with RTK. They’re similar! But not that similar. You’ll create a lot of mental clutter tackling both at once. You can only do so much.
That said, the biggest difference is that one’s an app and one’s a book. It’s a difference in values.
On the one hand, WK is a total package. You get a huge vocab list, kanji, native-voiced readings, pre-written mnemonics, ready to go. And the SRS gets you 80% of the way there with 20% of the work. You don’t have to think. The computer does a lot of work for you.
On the other hand, RTK is a book that shares a set of instructions. You have to think, a lot. You have to write mnemonic stories. You could use it with flashcards, even an SRS. But it works best if you sit down with each kanji and devote a lot of time to really visualizing it. It’s about quality of engagement, not speed.
RTK was born in the 70s. I imagine Heisig at his Japanese school, skipping class, turning over the kanji in his mind, no distractions, hours and hours every day. Meanwhile, WK was born in the app/internet/smartphone era. Nothing but distractions. WK’s main values are convenience and speed.
Put another way, RTK asks you to spend a half-hour of quality time with each kanji so that you’ll never forget it again. WK asks you to spend five minutes with each kanji, and then 10 seconds with it over and over again spread out over six months. After that you’ll 'burn" it and still eventually forget it, but you’re getting a bunch of vocab and leech training scripts and reading by then too. So you hopefully won’t forget it!
And you probably won’t, since WK really increases as a workload. The reviews are going to come for you. A lot of the quality time RTK would ask for will get eaten into by the piles and piles of SRS flashcards WK is going to lay on you. You can meditate on the kanji in RTK’s mountain hut or you can see them over and over on WK’s express train.
So I strongly suggest not to do RTK at the same time as WK because they do not complement each other. You could do all of RTK first in order to eliminate a lot of WK. I basically did that accidentally. I’ve gone fast because I just skip WK’s radicals and mnemonics. But if you do them both at once, you are repeating work. It’s like digging one hole, then digging another hole, and filling in the first hole with the dirt from the second hole, and then planting a tree.
All you want to do is plant the tree. Either hole will do.