I thought you meant diminishing difficulty WITH each NG. Within the same NG, after you get through Saydhi, you do get full health back (like in the beginning of every RB) and also the difficulty drops since you have money to buy Nova Grinder and other items. It goes up/down in the 5RBs after that, depending on which titan/deathless you face, then it goes up a notch again with GK as the finale.