Is it necessary to use the WDT techinque with a Macap M5 grinder?
I get a 3-4 few small lumps (5-10mm diameter) of coffee when grinding for a double shot, they are very soft and fall apart by even a light touch. Would they make any difference in extraction, they are compacted by tamping?

and another question, what about grinding into vessel, weighing, stirring WDT-style and then transfer to portafilter basket after that.

What you miss from doing the stirring in the vessel, is the distribution part of WDT but the clumps are broken up? Like a WDT-light? or is it just stupid?

It's the Weiss Distribution Technique, not the Weiss Clump Breaking Technique. If you can dose into your portafilter evenly and then preserve that bed with a decent tamp, then you don't need the WDT. That is a lot easier said than done. It really is about creating an even distribution within the portafilter. This is why I would say that the concept of dosing into a vessel and then pouring into the portafilter doesn't make much of a difference (unless you are doing so for weighing purposes).

I use WDT on a regular basis. It only take about 20 seconds and can't hurt, especially when I am still in morning zombie mode.

The M4 has a smaller hopper than the M5 which is smaller than the M5plus
All use the same 250W 58mm burrs 'grinder body'

It's important to clear the grinder chute and purge a second or two before grinding in earnest. If this is not done, then several grams of coffee are a'staling and form a significant portion of the dose. When single charging, grind a couple of grams to clear the stales if the grinder has sat for much longer than 15 minutes.

A gentle side to side shake that 'vibrates' the PF head is all that is required to distribute the coffee. Hold the PF loosely and shake the wrist as if palsied for a second or two. A light rap or two on the counter with a tamp [optional] and you're good to go.

In over 5 years of M4 use, the WDT has been useful with only a couple of coffees that refused to distribute with the shake

cafeIKE wrote:A gentle side to side shake that 'vibrates' the PF head is all that is required to distribute the coffee. Hold the PF loosely and shake the wrist as if palsied for a second or two. A light rap or two on the counter with a tamp [optional] and you're good to go.

This is how I have tried to do it, but I always get a couple of big spots in the extraction where the flow is much faster and blonds 10 seconds before the rest.

Now im trying out WDT to distribute to see if it improves, from the first tries it looks like an improvement but not 100% abolished the early blonding spots yet.