I agree but for me watering in the centre of root system is useless. I speak from my experience. Maybe there is a better way. I would say is also dangerous for root rot and if the center of root system is overwatered can hold the moist for over 10 days and the plant shows overwatering symptoms even if the pot is complete dry. That's how I killed lots of plants in my first grow.watering is a skill that some people dont think about.
You need to water thoroughly and evenly and try to maintain the consistency of a moist cake that sways from a little bit too moist to a little bit too dry.
and yes you should water the soil totally when doing a transplant or something so you dont have dry spots that justs channel the water to the bottom. Then leave it alone till you get to that cake moistness and try and maintain that.