This varies greatly with the area to be inspected and the type of NDT inspection that needs to be conducted. In some cases, robots can be faster than human inspection, but in general, robots are slower at completing the inspection task itself. However, factoring the time it takes to prepare, mobilize, and permit a confined space entry (CSE), robots will be faster. This means less downtime. Finally, while being faster considering the total scope, robots are safer. Eliminating CSE is a major reason to use unmanned drones. an answer here.