That's a neat head canon. For mine I like to draw from my own succubus universe idea. In mine, succubi can't get all the "nutrients" they need to survive unless they kill every now and again, so they can't "spare" people too much even if they wanted to. But, necessary or not, aggressive feeding wipes out the food supply like vampires. (My succubi can be very powerful sorceresses like usual, but they can't feed on mana alone. This ends up making logistics their true final boss.) So there are times when they have an excess of magical power but limited food stocks making it easier to keep mana to revivify a particularly durable victim (with or without amnesia) and farm them in a feeding loop until they eventually break permanently.
So if you play a particularly suicidal style, it's almost like maybe this guy even -asked- for this, but its not fun enough if he remembers everything in detail so he has partial amnesia to keep him confused and half-fighting half-succumbing. Depending on the level of psychosexual horror any particular group of succubi want to do, they absolutely could leave the drained bodies of other victims, or even the recurring victim's, around for decoration.
