If you search YouTube for V60 brewing videos and guides you’ll find about three billion different ones. Some with agitation, some without; pouring fast, in the middle, making circles; 40-60 or 30-70 or whatnot.
I always think to myself that they’re mostly just fluff.
It all depends on grind size and temperature. Doesn’t matter how you pour (well, within limits I would think) as long as you get your temps and grind right for the pouring technique you’ve chosen.
Admittedly, I haven’t tried a ton of different ones, maybe three or four. But this is the feeling what I’ve got.
Maybe there are some edge cases, like Ethiopian coffees being more prone to clogging the filter so less agitation might be a good idea.
i think you basically want some amount of agitation at some point relatively early in the process just to make sure all the grounds are getting wet. then you usually want less in the middle/late phases to avoid clogging as op mentioned, since the undisturbed bed slows/stops a percentage the fines from reaching the filter, and the reason you want to avoid clogging is that you cant get as good of a result if it winds up running too slow overall.
pouring technique can definitely have an effect on all this (e.g. pouring too hard in the middle to late phases with a shallow water level digs into the coffee bed and churns it up causing a lot of agitation).