To me, herbal nodes tend to me more subtle than mining ones, so I have herbal tracking on my main toon and mining on my second for when I'm just running around questing but want to gather nodes I run by. I glance at my second toons minimap occasionally but don't think I'm missing much ore just by keeping my eyes open (I have also set the distance view settings to the max detail level on my main toon).

When I get my flying mounts it would certainly be nice to have both tracking nodes up on the same minimap, but ofc you can't do this even on a single toon.

It looks like just running dailies and just buying mats is the most effecient path for multiboxers by far anyways, to be honest. With 5 shamans, I ought to be able to make about 750g in a couple of hours, which is a lot of mats. Although I did level up my herb and mining cause I hate leaving nodes in instances behind.