Guessing the issue is around “AIM FOR MORE” at roughly 52 minute mark.
Matt gives some recommendations that will help with extracting more, but the overall premise to “dial-in” is to over-extract and then dial “back” till it is not. Hence, extract more. Otherwise, most just stop at good enough which really can’t know, until you hit the limit of extraction.
“Extraction” though is sometimes treated as an absolute. A completely known quantity. From a certain perspective, it is. However, when balanced with subjective evaluations then this becomes a bit murky.
Meaning that it is very valid for flavorful coffee to have varying degrees of extraction that highlight specific flavor profiles that are what the coffee bean can best express.
Some coffee, no such thing exists. Personal story, I requested the pods of coffee from an American Airlines flight from the flight attendant to brew at home. These are the actual ones they use in their plane’s coffee torture/brewing devices.
There is no extraction on this planet or even neighboring parallel universes where this can be flavorful, as judged by any reasonably sentient species.
Top tier coffees from BH subscription generally have various optimizations for flavor profile extractions.
So, always better to extract as much as you can, but that is no guarantee at all of best flavor for that coffee.
So smaller grinds better, though water flow is problematic when too small due to micro-channeling, and also dosage size (bed depth) becomes a real problem at this point.