The thing is that you are limited by one fruit tree run daily. For most other skills, 30% more cost for 11% faster isn't worth it because you can just spend 11% more time. You have to take limiting factors into consideration. All things said, it's a very personal decision, and I can't be bothered to do the calculations to see if it's really worth it. Anyway, herb runs are always worth doing. I just suggested 2 daily because most people play at least 90 minutes. I would also recommend doing bush runs and cactus picking whenever you can.