No. Iirc, more NP only increase heals per turn, so it's not worth it considering the SQ and probably you have another target.

NP2 only gets you an extra 500HP. There might be a rare as heck scenario where that extra 500HP will save you, but gambling a shot at Castoria is not worth it.

She'll get a banner in about two weeks, so spend accordingly, I suppose.

I'm already prepared, but nervous, I reached the Pity Summon limit, but I now have 949 SQ and 21 Summon tickets.

It's my 3rd attempt and I can never fail in getting Castoria.

Well aside from that, there is also the perk of having the NP gauge not being capped at 100%, making it so that an NP drain may not outright prevent an NP from launching.

I am still unsure whether this and also the aforementioned heals per turn is significant enough to warrant an NP upgrade