I’m at level 31, right where you were planning to quit, and I’ve been reading daily since level 22 (and trying to read/decipher since level 15 or so). Now that I’m here, I know that I can’t stop at level 30 as there are still too many unknown Kanji showing up in the texts I’m reading, and the vast majority of them are in the WK 30s. But what I did was slow down. I was completing a level every 7 days until I hit level 30, and I now slowed down to a level every 14 days to give me more time to read.
I’m planning to stop my WK lessons, but not reviews, when I finish level 41. I looked at the charts and there are almost no elementary school Kanji left after level 41, and the remaining will only dribble in, one or two a level. So, the Kanji in levels 42-60 will be rare, at least for the level of reading that I’ll be in for another year or so. After level 41, I’m planning to just learn the Kanji as I find them in my readings instead of learning them in WK and risk forgetting most of them because they won’t appear in my texts.
But I’ll make that decision when I get to level 41. Which brings me to a point: you are still at level 8, too early to spend much time thinking about this. The vast majority (90%+ ?!) of WK users quit before level 30, so chances are, you will quit before level 30 anyway. So, get there first, then assess.