What does superthrive help with most (roots, plant bouce-back, etc)?

I read somewhere on a thread that topping off the res goes smoother when you add nutes, CM and LK in rotation to each other. For example:

1 top off with CM
2 TO with NUTES
3 TO with LK
4 etc


also, do you fill the res completely to the top with water on a top off (sounds obvious) or can you top off with less and less until you have to change the res (this would save labor and money on water)...are both methods acceptable?