Adding content starts to dilute authority the moment a new page stops deepening coverage and begins producing something thin, overlapping, or off-intent, so the working pivot is simple: does this page add distinct value, or does it merely repeat the cluster? The assumption that more content always builds authority holds only while each addition closes a genuine gap. Past that point, extra pages do not extend your coverage, they crowd it, and the topic’s overall quality signal weakens rather than strengthens. The turn happens not at a page count but at the point where new pages stop saying anything new.
The first form of dilution is thin pages. When you have already covered the substantial questions and keep publishing to keep a cadence, the later pages tend to be shallow because the meaty material is spent. A scattering of thin pages within a topic drags on how the whole cluster reads, signaling that the coverage is padded rather than deep. The page count rises while the perceived quality of the topic falls, which is the opposite of what more content was supposed to do.
The second form is overlap. When a new page restates a sub-question an existing page already answers, the two compete for the same intent, split the signals between them, and cannibalize each other instead of adding reach. You end up with two weaker pages where one strong page stood, and the redundancy tells a search engine the cluster is repeating itself. Off-intent pages do a related kind of damage: pages bolted onto the topic that do not actually match what people search blur the focus and weaken the coherence that made the cluster authoritative in the first place.
So the line to watch is whether each prospective page covers a genuinely new sub-question that no existing page already owns. If it does, it deepens the topic and adds authority. If it only repeats, overlaps, or strays off-intent, it dilutes, and restraint serves you better than another publish.
Before you add the next page to a topic, name the specific sub-question it answers and confirm no existing page already covers it well. Add the page only when the answer is genuinely new, and let the cluster grow by depth rather than by volume.