Combat is easy as fuck, even easier than what you can cook up in rpgmaker, the only somewhat challenging character in the entire act1 was Tsunade herself but even her i defeated without problems, all i needed is stun and poison skills, didn't even use my 500k ryo weapons scroll which would hit her for 50k damage, more than her hp and then some, 300k would have been enough and unleashed during her phase2. Anyway, yeah. If you plan on doing combat... maybe take your time with it or don't bother at all if it's too much effort.
I hate half-ass
We had pretty different experiences...
Although, having maxed out may have helped you a bit.
But again, when I finished act 1 only the skills from the 4 younger girls ans Shizune were added, so that may have made it harder. Used the others on Act 2 though. No Kurenai ilusion, Anko's cursed Seal or later Tsunade's boost for me.
Personally battles for me went between long and boring for the missions (after you are strong enough to survive even the harder ones, it still takes some turns) unless you aim for the luck-based skill, I'm guessing Kurenai's, that seems to kill in one hit
when it works, to a bit too hard without preparation like using the money from costumes/gacha for costume ingredients to fill a scroll for Tenten's skill. Which I did not do.
But of those that gave me a hard time, using basic attack seemed to be more worthy time-wise, especially since the chance of Ino's paralysis lasting more than the very turn it was used seemed pretty small.
Heal, as you said, not worth it.
Poison, added a bit of damage but not enough to compensate the change in damage from just punching.
After they appeared, using two turns to unlock Anko's and Tsunade's skills and double-buff attack seemed much better... after I could use them.
I definitely am not sure how I defeated Tsunade at the time. Since she seemed to regen at every end of turn more than I dealt damage. And I lacked Kurenai's one-hit-kill or Anko's hp-for-power-boost. I did my best with Ino's paralysis, but it sometimes lasted only that one turn if it even hit.
Also really dislike the battle system itself. Especially since I have to click in everything, even the enemy even when there is only one.