Please take into account the actual properties of what you are using when you make herbal potions. Sure intent is really powerful, but if you put a bunch of caffinated (or similar like mattinated, etc) herbs into a drink it probably won’t work as a relaxation potion on most people regardless your intent.
There are both the physical properties of herbs and fruits and other materials, but just as important are the spiritual properties too. This involves various forms of divination or spirit communication to ask the plant what it is good for. One way is to look at the shapes of the plant. A plant with leaves shaped like lungs could spiritually be good for lungs.
Even without magical intent from the “cook”, the physical and spiritual properties of the materials will still work. Because we are not the only beings in the world with “intent”. Plants with poisons in them “intend” to ward off the types of creatures that eat them without spreading the seeds nor helping them. Plants with fruits and upper qualities to them “intend” for animals that will spread their seed to new habitats to eat them and go forth. Those are some very simple examples, but it goes much deeper than that when you take into account animistic principles.