Not as a blanket rule. Whether repeating the head term helps or hurts comes down to one thing: whether the pages sharing it also share the same search intent. The term itself is not the trigger; same-intent overlap is.
Repeating the head term across a cluster is genuinely useful for consistency. It signals that the pages belong to one topic, reinforces the theme to both readers and search engines, and keeps your branding of the subject coherent. As long as each page that carries the term is answering a different question, the repetition is doing the work of topical cohesion, and there is no conflict.
The trouble starts when two pages carry the same head term and also chase the same intent. At that point they stop reinforcing each other and start competing for the identical query. Google cannot tell which one to rank, so it splits the signals between them, and both land lower than a single focused page would have. That is keyword cannibalization, and it is self-inflicted: you have set two of your own pages against each other for one slot. It gets worse when the pages also share near-identical framing, the same opening, the same structure, because then even their content blurs together.
So the line is intent, not vocabulary. Keep the shared head term wherever each page targets a genuinely distinct intent or subtopic, where the repetition reads as one coherent cluster. Break it up wherever two pages would otherwise collide on the same query, and differentiate the title to the specific angle each page owns, so each one claims its own intent instead of fighting for a shared one.
Across your cluster, sort the pages by the question each actually answers. Where the questions differ, let the head term repeat. Where two pages answer the same question, that is the pair to retitle, because repetition with differentiation builds a cluster, and repetition without it eats your own rankings.