It's a range collected from various opinions and articles, nobody demonstrated so far that a certain value should be the red line.
It's about taste and personal preferences, after all.
I am using the numbers only to check how different is a new coffee grounds distribution versus the older coffee.
Depending on result I might change 1-2 clicks, plus or minus, then the taste will decide if the right choice, not the numbers.

Got It. Thanks a lot! Anyways, I was wondering If JE-plus was a deadend for filter coffee.

Nope, check Timemore Chestnut X new burrs S2C "spike to cut" design, they claim an incredible low amount of fines.

Now I'm interested in the Kinu - has anyone done a back-to-back with the Kinu and JE Plus. It sounds like grind quality might be similar but Kinu is much faster & takes more force & much fewer rotations than the JE Plus.

40 seconds for 16 grams medium-light, with 11 kg force for 10 cm handle length.
You can easily measure your force for yours, using a luggage scale, using the hook/strap, to move the grinder handle.

Can't comment about "much" faster, I don't know any grinder needing more than one minute for such task.
Kinu surely requires a lot much force than others, Feldgrind for example needs only 4 kg force for same handle length, and only 5 seconds more, because the lower force allows you to grind much faster.

The above are valid for the standard burr though... the brew burr of Kinu is significantly different.
Good for kids and ladies as force, but much much longer... almost double time.