Thanks for this post. It struck a chord in me.
Props for returning with a new strategy and not going on indefinite hiatus! Pressuring yourself to tackle all lessons as soon as they’re available will definitely lead to burnout for most people, myself included–I’ve been there. The method should never suck the fun out of what is most likely a personal interest and not something you’re obligated to do. 
I’ve personally never focused on the Apprentice count. I’ve only ever done my reviews whenever I see them available and otherwise try to maintain a personal goal of n lessons per day, where n was usually 10. I say was because I am changing my pace as of this level, but I’ll get to that in a moment. My previous strategy of ~10 lessons per day and all reviews each day for the last 9 levels has turned into a bit of a slog when vocabulary floods in, leaving me without new kanji for longer than I’d like (using the default WaniKani item ordering).
Before I talk about my strategy change, I’ll mention that I find my current approach effective. I have active/passive Japanese input going on in various mediums, and I do catch myself understanding more in the wild as I learn the vocabulary for each level. I find the whole ordeal rather slow, though, and in order to speed things up, the default WaniKani would have me do what we said we didn’t like, which is to tackle a ton of lessons in one sitting to shift content from lessons to reviews.
I recently discovered the AJATT (All Japanese all the Time) philosophy, and it resonates deeply with me. So I’m trying a hybrid approach now. I’ll be using the reorder script to focus exclusively on radicals and kanji meanings and some readings (perhaps picking up some vocabulary here and there when I have no outstanding radicals or kanji). When I reach max level, which is sort of the AJATT equivalent of finishing RTK (Heisig’s Remembering the Kanji), I will start to pick sentences from my Japanese inputs to learn vocabulary in context and to fill the gaps in my missing kanji readings.
This will be an experiment, but if all goes well, I will be “Not-so-slowly and steadily levelling up” too 
I’m glad to hear you’ve hit your stride!