Is the requirement of crack width limitation (<0.5mm) be effective in control ling reinforcement corrosion?

In many standards and code of practice of many countries, the allowable size of crack width is normally limited to less than 0.5mm for reinforced concrete structure to enhance the durability of concrete. The limitation of crack width can serve the aesthetic reason on one hand and to achieve durability requirement by avoiding possible corrosion of steel reinforcement on the other hand. Regarding the latter objective, site surveys and experimental evidence do not seem to be in favor of the proposition. Beeby showed that there was no correlation between surface crack width (<0.5mm) and durability of reinforced concrete structure. In practice, most corrosion problems are triggered by the presence of surface cracks parallel to the reinforcement instead of surface cracks perpendicular to the
reinforcement.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.