I think they are little conservative, most folks are.

PO4 at higher levels to rid certain algae species was a long known thing.
I'm prettty liberal with dosing KH2PO4.
Generally rather high levels.

You can mentioned it and explain.

Hard to go wrong with K and PO4.

NO3 seems to be the only thing folks ever worry about anyway.
Like that's bad or something.

They generally make it dilute, so folks do not OD and also so folks use more if they have denser planted tanks, remember many only have 10-25% of the tank planted in many cases as far as the general public aquarium owner.




Regards,
Tom Barr