Why they exist
A page built for one campaign, with one message and one action, converts better than a general page — the audience is known, the promise matches the ad, and there is nothing else to click. That reasoning is sound.
How they go wrong
Landing pages accumulate. Two years later there are forty, built in three tools, none maintained, several contradicting current pricing. That contradiction is not just untidy — it is material a model may quote back at you.
Every landing page you don’t maintain is a page telling someone something you no longer do.
Keep paid, retire it after
A page built for a specific paid campaign should be excluded from indexing and taken down when the campaign ends. Its job is conversion for known traffic, not accumulation.
Organic belongs on your main site
Anything meant to attract search or AI-search traffic should live in your normal structure, where it inherits your authority and can be cross-linked. Standalone pages outside the site fight your own domain for the same query — the dilution behind content pruning.
Same system, fewer exceptions
Build them with the site’s components rather than a separate builder. Off-system pages are the ones that break on mobile, miss the tracking, and quietly go stale — and they will not respect the brand rules that must not break.
Give every one an expiry date
Decide at creation when it comes down or gets reviewed. An owner and a date is the entire difference between a campaign asset and a liability you find during a redesign.