Regarding letting coco dry out in general: The hand watering coco thread mentions in the first post not to do it, and to water often. But it may be that this only applies to plants with a more developed root system (I overwatered my girls at the first watering after planting the clones).
Something I have not mentioned yet: The clones were rooted in rockwool, and I buried the rockwool in the coco. I don't know if there's another way to do it, but it seems like it might play a role with the overwatering issue - I would guess that rockwool is more prone to overwatering than coco.