The US Citizenship and Immigration Services advised its officers to "apply the same level of scrutiny" to extension requests for the H-1B visa, among other sought-after visas.
So in essence, officers must review requests for renewal as thoroughly as they would for initial visa applications. And, requests to extend visas will be checked for eligibility again, even if all details in the application are unchanged from the original one.
Here is the full text of the notice:
Policy Memorandum
SUBJECT: Rescission of Guidance Regarding Deference to Prior Determinations of Eligibility in the Adjudication of Petitions

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