Q: Would It be better to dose NPK over several days or just once when I do the WC?
I was wondering this myself so I don't have an answer for you. I can't imagine it would make much of a difference to dose NPK all at once vs half doses spaced out during the week. I don't think plant uptake is that fast, and it's not like the ferts become inactivated after sitting in the water column for so long.
Does anyone have an educated answer to this?