For bare-root vandas, I spray water first to open up the roots and then spray 1/4 strength fertilizer during the morning watering. At night they just get water (go to bed hungry). I may try 1/8 strength twice a day.
For potted Catts and Phals, I run water through the bark for 10 seconds or so, then I run one pot volume worth of 1/4 strength fertilizer through the pot. This happens about twice a week since it's summer, the clay pots have holes on the side, and the bark seems to dry fairly quickly. It seems to be working well so far. No sign of burnt roots (fingers crossed).