
Is using everything to fight a boss worth it?
So I just got to the Guardian Ape, and from my opinion and others', it seems like this is a hard boss fight. Phase 1 is easy enough, you just have to be patient. But the problem with me is Phase 2, when he can deal damage through his scream + has very little stunned room to attack, leading to me having to deflect a lot more attack (which means more chance to get hit). With that, my health just decreased like crazy, so I had to use all the healing items including 1 Divine Grass as well as all the Ako's sugar and almost all pacifying agents I got.
Now I fear that if later there is a harder boss, and I got none of the good items with me, how am I gonna fight? Is there anyway to get more (many) good items like the Divine Grass, Gokan's Sugar, or Ako's Sugar? If not, should I try to save up my resources as much as possible, which means getting perfect fights using just Healing Gourd or plentiful items? (I kinda did the same in TLOU tho as it also had very limited items)
PS: This is my first soul game (1st time seeing the enemies respawning after rest + using items then dying means they were for nothing)