you waste your time alot of the while because your picking these plants, experimenting with them, and having a high chance of actually losing that herb and not getting anything out of it.
See there, you think it is a waste of time. Make it meaningful. Here is what I do:
-Anytime I decide to mess with alchemy (which is usually when I want to get a level up quickly) then I will throw a map marker in a certain, undiscovered area of the land. I will go in search of plants to bring back and train my alchemy.
-When I go to certain city, I will set a land marker in a certain area (close proximity) to the city and just go gather herbs from the area.
It's quite fun, you get to encounter enemies, discover new places, random encounters, a whole bunch of things. Try it.