Consecutive hits/speed up buffs are really only good for your first NG run I feel. Combat arts and spells are so overpowered comparatively speaking, that mashing out combos feels super inefficient. My first AG run Sylvian carried the run; subsequent runs had him resort to a bologagne/ragnarok bot. You could just run up to a base commander, use a spell, and then run out. Combo move sets just become a filler while waiting for a spell cooldown.
Because of this, I personally just rank units on who can one shot the most consistently with the least investment. This usually results in units like Byleth and Yuri, etc… who gets impossible feat, lifeforce, dual onslaught, and decent growths, ranking high for me. While unfortunate, min/maxing doesn’t seem to yield much results compared to just playing who you like. Whoever can one shot the most consistently just becomes the most efficient. If they made cooldowns much longer on combat arts and spells, the conversation would be drastically different I feel.