Nailed it, dragonmere. The three keys to being a good hull engi are knowing when to switch from spanner to mallet, switching to spanner in the cooldown where the armour is about to go down, and switching back to the mallet almost simultaneously with your final spanner rebuild hit (note: right after the rebuild is over. I know that some people like to finish the rebuild with the mallet, but that just slows it down a lot) in order to save a fraction of a second on that first repair hit.