If you haven’t read it yet, I highly recommend taking a look at the ultimate guide to WK. There are lots of tips in there about creating an effective schedule that works with the SRS intervals and fits around your life.
I’m going about half full speed (so, about two weeks a level), which is the perfect pace for me, since I’m learning a bunch of additional vocab and grammar at the same time. I do 10-12 lessons every single morning (along with reviews from overnight), then do my reviews four hours later, then eight hours after that. The pressure of wanting to hit those intervals helps keep me from procrastinating, because I have a very precise window of time that I need to study. I’ve been doing this for long enough, I’ve formed a strong daily habit, which helps me keep it up even on bad days.
I’ve seen a fair amount of people burn out and quit, and it seems like the people who have had the most success tend to be the ones who craft a really consistent workload that they’re able to stick with every day.