I don't understand the use of Leftovers numbers in this case, because the optimization problem is overall defenses while the constraint is a small amount of Speed EVs. Leftovers numbers are only useful when the constraint is a large amount (>256) of non-HP EVs, in which case you have to maximize the efficiency of each quadruple of HP EVs you choose to invest. in this case, we aren't constrained by the need to save too many EVs for Atk/Def/etc which means it is more efficient to just maximize HP.
the only deviation from this would be when there is a specific threat that you need to cover on either the physical or special side (to avoid a 3HKO or something). in that case, you would compromise overall defenses to enhance one specific defense. but if there is nothing of that sort, maximizing HP is best.
the only deviation from this would be when there is a specific threat that you need to cover on either the physical or special side (to avoid a 3HKO or something). in that case, you would compromise overall defenses to enhance one specific defense. but if there is nothing of that sort, maximizing HP is best.