Nope, it doesn't (on its own, at least)
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-f, --flash is what makes (pretty much any combination of other things: i.e., --refresh, --image, --truetype, --clear, --cls, ... you get the picture: all the things ;p) flash
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IIRC, it *does* consume slightly more power, but I'm not sure if it'll have a (really) noticeable impact. My gut feeling would be that one flash would drain less power that two non-flashing updates, though, to answer your question.
Also, some waveform modes *might* be less power-hungry. f.g., you can probably make do w/ DU (which is probably what AUTO, the default, will choose on its own anyway).
And, speaking of wfm, A2 can't flash. Enabling flash will make it try to ghost less on most devices, but it won't actually flash. Just mentioning this for context, as A2 has a really niche use-case, so you probably don't want to use it unless you *know* you want to use it
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(And, with FBInk, it probably wouldn't help on the power consumption side of things, as we enforce monochrome for A2 updates, so that's another PxP processing pass tacked on by the driver).