As mentioned, fletching is only meant to induce drag on the tail of your arrows, helping to keep the tail in the back and the nose in the front.

If this drag isn't even on all fletches, it will impart uneven pressure on the tail of the arrow, causing a slight torque deflection (pivoting at the center of balance) on the tail, actually increasing your wobble.

Now, if you've ever fired arrows with damaged fletching, you've seen how little this matters on a well tuned bow. For what it's worth, the only reason I fletch my arrows at all is to help me find my arrow after a shot and out of habit, as I could deliver "huntable accuracy" bareshaft with Rages out to 40yrds without any fletching at all.

Ultimately, in a physical sense, having uneven fletching hurts arrow stability, so it's mostly just a fad.

On the other hand, if you want to slow your arrows down, like a flu-flu, having uneven fletching can help do that, but your accuracy will suffer.