It’s never fully out of control, it may only feel that way.
People have come back from 3000+ reviews due, there are a few threads like this one:
Spoiler alert: He did it 
I feel like people are worrying about their review count too much.
All you can ever do on WK is doing as many reviews as you can.
You will steadily improve your kanji knowledge with each review, and get closer to knowing all of them.
It may not feel that way, because you keep doing new lessons, but the work to do factually gets less.
By the way, you said the pace is perfect for you, otherwise i’d also have recommended doing fewer lessons.
Currently I’m looking at this:
But i’m completely calm, because i’m always calm i know it’s just a matter of time until i’m done.
Now, back to reviewing (=