I get the whole moisturizing your hair while it is in cornrows... my question is what about the inner part of the cornrow? Especially if they are the large ones. Does what you use to moisturize penetrate?
I've wondered this myself, OP. To be certain all of my hair gets moisturized, I like to cowash daily to every other day while my hair is in the cornrows then seal with oil or butter of choice. This way I know my hair gets the moisture it needs to thrive.
I would think the hair that's tucked away looses the least amount of moisture (it's more protected) so it should need less to replenish.