how it seemingly had no obvious routine to it.
It's amazing how much complexity can emerge from relatively simple rules! It definitely feels much more random for free members like yourself, because it takes time for enough pending balance to accumulate to support each $0.021 upvote.
It has typically been a more consistent experience for members with enough voting units to assure an upvote on every post (although things are weird right now! we will go into more detail in our next planned post).