I don't think he is necessarily 'milking the system' with his disappearance. Mental health is very complex and entirely non linear, so you can go for periods where you feel a lot brighter and then the slightest thing can set you back. I am not excusing any of his behaviour, but I personally believe (and yes it is just an opinion) that he attempted to take his own life and is recovering in the aftermath. In any case, none of us can really know the truth and all of this is just speculation. But I'm not personally comfortable with dismissing his illness just because it's not a wholly physical disorder.
Schofield can get in the bin mind, with all that passive aggressive bullshit about knowing how Caroline Flack must have been feeling.