How many loose screws does Eminem have?

In Eminem's new album Music to Be Murdered By, a phrase returns that has made an appearence in several of Eminem's works throughout his career.

2000 – Eminem – The Real Slim Shady

Yeah, I probably got a couple of screws up in my head loose
But no worse than what's goin’ on in your parents’ bedrooms

2002 – Eminem feat. 50 Cent and Obie Trice – Love Me

I got screws loose, yea the whole kit and caboodle, I'm just brutal
It's no rumor, I'm numero uno, assume it

2004 – D12 – American Psycho II

I probably got a screw loose or two
Or maybe three or four of ‘em

2020 – Eminem – Never Love Again

So I refuse to, might have a screw loose and a fuse blew
But I think I might be buildin’ up a tolerance to you

So far, I've found four uses of this phrase (which is fewer than I seem to recall). The phrase is always used in the same context, refering to himself.