They way i have always done it, is to feed enough for the slightest nute burn. If or when i see nute burn, especially if its happend so soon after the first fert. I will cut the time between feeding down, sometimes stop completely. The plants will benefit more being slightly overfed, but too far and you will hurt growth. How often you fert will depend on the plant, age, soil etc. Feeding with every second watering is a good start, close watching will tell you wether you need more or less. Bad soil can have you feeding every couple of days, great soil can have you never feeding it. Its all about watching and hearing what your plant needs.