As they grow their nutrient requirements as well as the frequency changes. You need to keep up with the life cycle of the plant as best as you can.

The deeper you go into flower the more nutrients your plant will need and use. It does look a little week on the N what nutrients are you feeding them?

If you have proper drainage you should be watering every 3-day's. If you can go 4 or 5 then you don't have enough drainage in your soil or enough drain holes for it to leach out.