Independent verification and validation (IVV) has been a key process for decades, and is highlighted in several international certification standards. Some require independent safety auditors, others require particular process objectives to be satisfied with independence, others force an independent testing team or quality assurance team, or even independent resources for several different SDP processes. In the area of IVV, recently ESA contracted the creation of an "ESA ISVV Guide" with the description of all the possible tasks that can be carried out with independence in order to guarantee maximum quality, but especially to gather all the good practices and define uniform guidelines on how to carry out IVV activities. One of those activities is independent tests verification (stated as Integration/Unit Test Procedures and Test Data Verification). This activity is commonly overlooked since customers do not really see the added value of checking thoroughly the validation team work. This article presents the results of a large set of independent tests verification, including the main difficulties, results obtained and advantages/disadvantages for the industry of these activities. This study will support customers in opting-in or opting-out for this task in future IVV contracts since we provide factual results from a few real case studies. Case studies details and companies involved are not disclosed for obvious reasons.