I bottom feed but you gotta do what you gotta do for the plant, As far as ive seen though as your plants grow together they start to dry out and need water at the same time. i know there's always the slow pokes, we try to avoid that by good mother/seed selection. Ill water all of them though even if one or two are still damp, seems those are always the ones that need water earlier next time. I like lots of perilite too, that helps avoid over watering