the thing with bush doctor is it is hard on the plants after you use it for a while. i speak from experience from using bush doctor.
i say if your plant is healthy you have no need to spray bush doctor.
spraying is used to help fix the plants deficiencies. if you spray you should just use plain water. the plants love it and stay healthy, so if your plants are sick, yes spray bush doctor once every other day and that is when there is something wrong. when you mix it with water the mix is good for up to 2 weeks, hope this helps, your plants look very happy though so precede
with caution if you decide to spray. happy growing