What do I need before this is useful?
The competitors you care about, by name and domain. That is enough to start, and it is worth saying plainly because the instinct is to go and assemble a list of URLs and surfaces first. Everything else, including which mechanism serves which page, falls out of the first pass.
How is this different from an alerting tool?
Alerting tools mostly do one mechanism, which is fetching a page and diffing a region. It is the last resort here, because it costs a request per surface, cannot date a change better than between two checks, and fires on consent banners and carousels. Nine of them produced 86 per cent noise in the example.
Why test the sitemap dates at all?
Because a build timestamp is indistinguishable from a real change feed until you count the values. Google's own guidance says it uses the date if it is consistently and verifiably accurate, and a competitor who fails that test is expensive to watch forever, which is worth knowing on day one.
Does this find anything before monitoring has run?
That is the first thing it does. One date per URL is a recency map, so it says which parts of a competitor's site they have stopped maintaining. Job posting markup carries the original posting date as a required field, so live roles reconstruct hiring volume by month for years back.
Why not just check everything weekly?
Because the surfaces differ by a factor of 16.5 in how often they change, so one interval is simultaneously right for one of them and twelve times too fast for another. And the cost is not requests, it is the reviewer: a schedule nobody abandons beats a schedule that is theoretically complete.
What stops the digest becoming a list of changes again?
The register reports hypotheses, not changes. Of 133 logged changes in the example quarter, 46 attached to a hypothesis and 87 touched nothing, which is the normal ratio. They still get logged, because the pattern that turns a batch of them into evidence usually shows up two quarters later.
Does this write the battlecard?
No, and the boundary is deliberate. This space detects change and interprets it, then hands the answer to a named person. The depth analysis of one competitor belongs in a competitor teardown, and the field-facing artifact belongs in a sales battlecard. A detected pricing change also invalidates whatever your published comparison page asserts about them, which is a separately sourced claim.
Competitor Register