As of October 23, 2017, a new policy regarding the nonimmigrant worker visa renewals will require the USCIS officers to scrutinize the renewal petitions the same way as the original petitions. The new policy applies to almost all nonimmigrant classifications filed using Form I-129 (Petition for a Nonimmigrant Worker). Thus, the new policy affects H-1B, L-1, O-1, etc.
Before October 23, 2017, adjudicators deferred to prior determinations of eligibility if the renewal application involved the same parties and the same facts as the initial petition. In other words, if your work visa was approved (absent a material error or fraud), chances were your renewal petition would have been approved as well, so long as there were no major changes in your circumstances.
As of October 23, 2017, the USCIS has rescinded the policy requiring the officers to defer to prior determinations in renewal applications of nonimmigrant work visas. Therefore, nonimmigrant work visa extensions will now receive the same level of review and scrutiny as the original applications, regardless of whether the previous petition was approved.