You're conflating two kinds of history (though they are of course intertwined, but I think a distinction is still worth making): how one person (eg. Freud) deve

You're conflating two kinds of history (though they are of course intertwined, but I think a distinction is still worth making): how one person (eg. Freud) developed their ideas over time (which, outside of literary or artistic contexts, isn't very interesting), vs. how some schools of thought (eg. Freudian psychoanalysis, Behaviorism) gave rise to others in response (eg. Humanistic psychology). Getting back to the OP's question, while some discarded theories can justifiably be ignored when studying a field (eg. in geology, anything prior to the general acceptance of plate tectonics in the late 70s), in some fields older theories and models aren't necessarily abandoned entirely (eg. the aforementioned Freudian psychoanalysis is still somewhat relevant for individual counseling) depending on the context (eg. you probably CAN skip Freud if you're interested in Behavioral Economics or Organizational Psychology), unless what you're really interested in is arguing about definitions (eg. there is no reason to pay any attention to Lamarckism unless you just want to argue whether or not epigenetic mechanisms that provide additional wiggle room for phenotypic expression across generations should be considered Lamarckian). So, it depends.