From http://singinst.org/upload/CEV.html, I added some emphasis to explain why I understand it the way I do.

Spread, muddle, and distance....

Spread describes cases where your extrapolated volition becomes unpredictable, intractable, or random. You might predictably want a banana tomorrow, or predictably not want a banana tomorrow, or predictably have a 30% chance of wanting a banana tomorrow depending on variables that are quantum-random, deterministic but unknown, or computationally intractable. When multiple outcomes are possible and probable, this creates spread in your extrapolated volition.

Muddle measures self-contradiction, inconsistency, and cases of "damned if you do and damned if you don't". Suppose that if you got a banana tomorrow you would not want a banana, and if you didn't get a banana you would indignantly complain that you wanted a banana. This is muddle.

Distance measures how difficult it would be to explain your volition to your current self, and the degree to which the volition was extrapolated by firm steps.

Short distance: An extrapolated volition that you would readily agree with if explained.

Medium distance: An extrapolated volition that would require extended education and argument before it became massively obvious in retrospect.

Long distance: An extrapolated volition your present-day self finds incomprehensible; not outrageous or annoying, but blankly incomprehensible.

Ground zero: Your actual decision.

...

Coherence: Strong agreement between many extrapolated individual volitions which are un-muddled and un-spread in the domain of agreement, and not countered by strong disagreement.

Coherence:

Increases, as more humans actively agree.

Decreases, as more humans actively disagree. (The strength of opposition decreases if the opposition is muddled.)

Increases, as individuals support their wishes more, with stronger emotions or more settled philosophy.

It should be easier to counter coherence than to create coherence.

So coherence is something done after un-muddling.