+1
IMHO/IME cartridge loading isn’t independent from general sound signature of the setup. It’s mostly related with phono stage’s sound signature together with amps, speakers etc. Admittedly every cartridge has a preferred loading, that’s for sure, I’m not questioning that, but other components also play a role on final loading value as
@Johan K said.
For example same cartridge may perform best at 50ohms on setup A and 200ohms on setup B. If you’re using an active phono stage it’s character is a decisive factor for loading. BTW SUTs are more tolerant for cartridge’s internal impedance but they also have their own sound signature. Too complicated.
When I read what I’ve written digital looked like a good idea.