I am 89% of the way to level 5 and for me since I am a beginner with Japanese in general as well as fall in that want to be a perfectionist category, I thought I would share my experience.
I have no time frame in which I need to learn everything, I am doing it by my own choice, not necessity. I do have goals on learning though, so I am not really just mindlessly wandering. haha!
I do lessons throughout the day instead of a big chunk at a time, but only do 3 lessons per session, but with radicals I would end up doing maybe 15 or so per day in lessons, kanji and vocab maybe 9-12 per day depending on what other grammar or outside wanikani vocab, or whatever else I may be doing in that particular day of learning.
So far I have been extremely happy with my progress in just over a month of learning Japanese. I have learned hiragana and katakana, completely. I have learned a ton of key phrases, as well as quite a bit of grammar, how to count, and other random things as well. And I am almost level 5 in WaniKani (should be by end of day). Compared to everyone else as far as speed goes, I would consider myself going twice as slow as everyone doing the 7 days levels. I take about 12-14 depending on how much vocab may be in each level. At the same time though, I am also practicing writing out all of the new kanji I am learning for retention, because for me specifically I want to be able to write them from memory, not just recognize them when I see them. But that isn’t for everyone, it is just a goal for myself.
So basically, I don’t think there is a too slow or taking too much time to learn. Everyone learns everything at a different pace, in different ways, and for different reasons. So basically, you just have to figure out why you are learning, how you are learning, and do you need to know it in a certain amount of time, or what goal you have for yourself with it to figure out for you specifically whether you are going too fast.
For me, if I take the time to do a lesson, I don’t want that time to go to waste, so I would rather feel like I am really learning something instead of just hoping I am learning it, but I know that way is definitely not for everybody…lol! Hope that gives it another perspective too?