[hunter2_]

But even if you're just modifying a DCA schedule slightly (buying a little early/more when things feel particularly cheap, or buying a little later/less when things feel expensive) -- doesn't the same problem exist: that those adjustments typically cause a worse outcome than if you didn't apply them?

Maybe some people have a better crystal ball than others, but if we just look at the average case where studies favor vanilla DCA, I have to imagine that the reasons (why DCA wins) will prevail regardless of the extent that they're applied. But if your skill is enough above average that it's helpful to deviate, go for it...