REF: de-duplicate operate-column-wise code, pct_change
hmm can u show perf changes here

is pct_change just dispatched now? > hmm can u show perf changes here

ill figure something out, not sure if we have any asvs that go through these paths

> is pct_change just dispatched now?

ATM the subclass implementation is effectively identical to the base class implementation, so this is just ripping out the unecessary one
