Understood. I hardly ever use anything but denoise (profiled). I was only asking because you mentioned using contrast equalizer.
But I accept your challenge and will try one day to invest time in working out how the module works and how to get even better results. I am just amazed that with my cameras the module works so much better in DT V4 than 3.8. In 3.8 I only ever did the chroma noise in that module. I am also impressed with how well DT handles noise in general. I shoot a lot of high ISO images with a compact camera because I like to wander at night down alleyways and through street markets when I travel overseas. That is how I got the sample image I have used here. I want a non-intrusive camera so I use a Canon G16. Also a 6mm lens gives great depth of field at f 1.8.
We also have similar cameras in the family (a Canon G15, (un)used by one of my daughters, and a Panasonic Lumix LX-7 that I use).
If the G15 is as good as the G16 you should hang your head in shame. 
How to Denoise effectively:
First instance should always be Denoise profile wavelets (chroma), and use the curves for a specific frequency range. Second instance should be denoise profile non local means, dial the strength of the module to your convenience, I almost dial it down to 0,5 strength. After denoise apply sharpen with the diffuse module or contrast equalizer for frequency sharpening.
I haven’t seen the need for chroma denoise - maybe it’s camera dependent. I use non-local means at half, or sometimes less, as low as a quarter. A tip I picked up somewhere, is to use contrast equalizer to remove the artifacts from the non-local means denoise. I sharpen with diffuse&sharpen only in most situations it is enough.
I do not understand why RAW denoise is not used more often - unless it’s just that people like to keep to the same setup when dealing with jpegs. I use RAW denoise at a half usually.
Can’t speak for others . But i find it hard to get good results with it. It overdoes it or leaves stuff in that makes it ugly.
If i find the noise a problem (not often ) , just enabling denoise profiled is often a single click .
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I do not understand why RAW denoise is not used more often
Perhaps it depends on what camera make you have?
I think it must. There must have been a reason it was written, and still exists in Darktable anyway.
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For me it’s the non-local means denoise that leaves ugly artifacts.
Speaking about this in the abstract is difficult. Some samples and some details of what camera would be useful.
Not really. If there is a certain group of cameras, types of sensor, RAW data types, that react well to Darktable’s RAW denoise, then it is better to talk about it in the abstract. To take one person’s experience with one camera would be ignoring a whole bunch of other possibilities, like preference, ability, usual workflow etc etc.
Multiple examples can be posted…
OK. So, I have a notably noisy Panasonic Lumix FZ80. I find it’s images react well to a little initial RAW denoise. On a very noisy image, some brighter pixels get missed and the “hot pixels” module takes care of them.
I also have two Canon cameras, a 600D and an 80D. They are less noisy, so RAW denoise is probably less likely to be necessary. However, it can be used and works well.