In 2013, psychologists Jordi Quoidbach and Daniel Gilbert (Harvard) conducted a study with a result that sounds almost unpleasant: people of any age — 18, 30, 50, 60 years old — admit that over the past ten years their values, interests, and personality have changed significantly. And at the same time, those exact same people are confident that in the next ten years they will change very little.
The authors called this the "end of history illusion": we easily see how much we have changed in the past, but subconsciously feel that right now we have finally become the "definitive version of ourselves." This applies not only to personal life — music preferences, the value of close relationships — but also to professional ambitions.
From here follows a consequence important for HR and career planning: a five-year career development plan drawn up today relies on a person who will no longer exist in two or three years — simply because the employee who drafted it will also change. What seems like an obvious goal right now — to become a department head, dive into deep expertise, change industries — will very likely not seem like such an attractive goal in an actual five years.
This is not an argument against planning in general. It is an argument for treating long-term career plans as a hypothesis rather than a contract — with regular revisions rather than a one-time fixation at the start. An annual honest conversation about "is this still what you want" is more useful than a beautifully drafted plan that no one ever reads again.