I use the leachate as a soak when I re-pot plants but can not take the time to soak 10,000 orchids on a regular basis.
I use it twice a month as a root and foliage spray. The microbes can be absorbed into the leaves directly.
I never see rot on Paphs or Phals and I spray just before dusk so the microbes are not damaged by UV sunlight. However, I do add Bracillus bacteria to my mix which is a natural fungicide.