I mean I can see where you're coming from, even if it's a bad example (derivatives of cocaine are extremely common today in medicine--procaine, lidocaine, etc.--but Freud worked with what he had at the time). Though its true that the entire psychological apparatus stands behind everything anyone ever says, writes, signs, for Freud, so it's impossible to read one part separated from any other, or to value one part more than another absolutely, instead of seeing it instead in a complex network of interwoven--as the French say--signifiers.

What your valuation (of projection over the use of cocaine in medical treatment) describes has more to do with the social and psychological economy from which you have received Freud as a body of texts and paratexts, than anything about Freud as a total system. What I've argued prior is that on account of the way Freud constructs psychoanalysis, and sets psychoanalysis as the means by which one can track their own place in discourse, means that everything is mediated psychologically, and therefore everything written by an author must be connected for that author. To take Freud, then, not as Freud as such, but as Freud as a body of disconnected texts, would be a disingenuous reading: still, possible, but not at that point Freudian. At that point, you'd be developing your own theory with reference to Freud.