The following are all myths and do not really matter
* Stirring during bloom
* The rao spin/stir
* Having flat bed at end of the brew
* Pouring in spirals - always just pouring in the centre is fine
Almost all the extraction in drip brews is through washing the surface, there isn't much diffusion happening so almost nothing happens during a drawdown. Whether you have flat bed in the end or not has no effect on the flavour. Unless of course you listen to the "evenness of extraction" gospel from certain coffee professionals. Messing with the slurry by shaking / stirring only pushes more silt into your brew. Also any serious agitation late in the brew seems to extract lot of astringent flavours regardless of grind size, I don't really know the cause for this.
* grind size and temperature (for obvious reasons)
* pouring speed and number of pours
Did you know that SCA has a comprehensive evenness of extraction test where they actually dry and test samples from different parts of the brew?
And brewers such as Moccamaster pass this test even though they don't stir or shake or do any of the things recommended. Have any of these people recommending evenness of extraction done any such tests?