Spoiler, its RDT
In case people do nto know what RDT is, which they really should if they have been into coffee for a little while as it makes a big difference:
RDT is Ross Droplet Technique, which is very much adding water to beans. Named after David Ross who came up with it back in 2005
They advocate for rdt over wdt as the most important? Interesting.
Wdt, for others in this thread, is a Weiss Distribution Tool. This is using a tool with some thin, flexible needles to break up the coffee after placing it in the portafilter.
I feel like if you do wdt without rdt, you’re fine. If you do rdt without wdt, you’re missing out.