The investigations demonstrate that minimizing the degree of backmixing represents a valid strategy to deal with Grignard reagents that are prone to the formation of Wurtz products. The elaborated correlations between the Bodenstein number and the selectivity towards the desired Grignard reagent product, that also includes batch syntheses, underlines the general applicability of the concept. This finding is of special relevance for Wurtz-affine reactions that require advanced reaction control, which, as has been demonstrated, can be realized with a suited reactor or flow conditions. Consequently, a change of the solvent and an associated in-depth change of the entire reaction system and potentially the product can be avoided. Furthermore, it is evident that Bo of 50 or above are required to lead to a significant improvement of the selectivity. A particular challenge is the realization of a narrow residence time distribution under reactive conditions. Since the magnesium bed participates in the reaction and the Mg turnings change their size during the reaction progress, knowledge gained for the non-reactive case cannot be transferred directly. The residence time distribution is much broader under reactive conditions and especially a manipulation of the hydrodynamics in the magnesium bed by means of oscillating flows strongly deviates. The inhomogeneity of the bed seems to be the most important parameter in this case, that governs the residence time distributions that can be realized.