You never want to let coco dry out. Coco has very good moisture & air retention & the roots need both. If the roots dry out it'll be a very stressful event for the plant. As coco dries the EC rises (nutrient salts don't evaporate) so drying out could also cause "nute burn" symptoms (dark leaves, burnt tips).
You want to water coco at least once a day with run off each time (20-30%). The run off helps remove excess salts from the coco / roots, pushes the old nutrient solution out (which will have risen in EC) & also draws fresh air into the pot (roots).
In theory watering coco several times a day would keep the EC more stable & provide a better environment for the roots / plant. I've only ever watered once a day (& I think most do) but it's something I'll experiment with as the theory makes sense.
The "coco for cannabis" website has detailed instructions for every aspect of... Yep you guessed it, growing cannabis in coco & is worth reading
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