The basic skill allows to search for mixed materials, but plant fiber is needed a lot which is why I think being able to search for plant fiber only (and those other materials) would be great!
Instead of having those steps being about herbs, make them about gathering materials. 30 might allow multiple (3-5?) branches being snapped off per action. Or specific search for materials on 60 and doubled amount gathered on 90.
Oh, and if someone is wondering about herbs? Leave that to the herbalists, making herb gathering the best way to level up to 30 or even 60.