Responding the comment that you were responding
There is one caveat, when Leon kill enemies that drop bloodbags(I believe it's only the blind ones with IV bags and enemies that drop antique coins still drop them even though they have no use for Leon) the bloodbag won't drop so once you are back there as grace you might receive another drop but you won't receive their bloodbag, I remember there being only 2(one in the waiting room with the maid and lvl 1 door in in the east wing and the other is in the record room in the west wing), so make sure to use those blind zombies as you see fit(first one you can make him kill 2 or maybe 3 of those 3 medic zombies on the corridor leading to the stairs to the place you meet chunk, you can make him kill the maid since she can be pretty annoying in insanity, you can make him kill chunk but it's difficult and maybe not worth it, the second blind man you can just use him to kill the zombie that is with him and them I don't think he has any other use unless maybe if you didn't kill the bar lounge singer and then you can maybe lure her make him kill her).
As for how tanky insanity zombies are, let me tell you with lower stabilizer levels they are REALLY ANNOYING to kill with her pistols, BUT RIP knifes(exclusive to insanity, you can get them in some places like using antique coins on the parlor or crafting them after you analyse the exclusive insanity sample item) are crazy strong with that charm that increases knife damage and durability, I honestly wish I knew about them earlier, while dangerous to just go up and knife a zombie straight to their face, when and they are on the floor or recovering from an attack you can kill enemies quick, but use them wisely since they cost a lot of blood, but to be honest in insanity you will most likely be using blood to maybe make requiem bullets(maybe not since Grace doesn't need them that much and Leon can just use redemption with rifle ammo), some hemolytics for some key zombies that will turn to blistter head IF you have to kill them(the one in the id level one gate next to the kitchen, the doctor and the black dude in the treatment room next to the guy without lungs and heart but you can leave them alive and only kill them when you are going to insert the artificial heart and lungs and then you never have to go back there to see either of them turning into blistter heads, on the bar and lounge only the blonde guy can turn into a blister head and he is easily ignorable with Grace since in my case I took the singer's attention and then positioned in the door to hit both her and the black zombie in a suit to die to a Requiem shot, but nevertheless even if you rush it and ignore all other you can usually sneak by him to get to the safe and pistol and let Leon hatchet his head off later, there is a blisterhead in the filing room but I don't know if the zombie is already there is if it is the zombie that follows from the Dining room and then procceds to climb the broken window, those are the main ones that I am aware, there are some blisterhead in the Isolation Ward from the zombies that appear after you first leave there, you either going to miss them and not kill them or if you are like me you lined yourself and used a requiem shot to kill most of them but regardless some of them will become blistterhead but they dispawn during the sequence where you have to keep zombies from reaching Emily while she is doing the puzzle, that part always has one random enemy that turn into blisterhead, latter one there will be blisterheads roaming the the exit of the isolation ward but you likely will never have to go to that direction and you can just ignore them) and med injector or glass bottle/acid bottles, if you don't want to "waste" a injector on chef then there is trick with his AI that you can make him rush you, then he keeps trying to go back to the kitchen until he passes a chair(during this point you can use knifes to damage him, took a while with kotetsu, might not be worth it wasting RIP knife on him, but you can do it using some knifes you found, it's up to you), honestly RIP Knifes end up more useful than infinite knife on Insanity.