WK leveling isnt random. Normal levels (most of them) have 2 sets of Kanjis. The first set which is made available right when you level up then the second unlocks when you Guru the radicals for the first time on that level. Only Kanjis (and by necessity Radicals) are required for levelling.
You can already set your own levelling schedule with WK. Read this guide to learn more. The only thing you cant do is going faster than the Max speed set by WK.