D6 is Redundant and Add Judgement at D5

Verification versus Validation in 8D Problem Solving
Ondrej Durej, Management Consultant, Slovakia
You must realize the difference between verification and validation:
Roughly speaking VERIFICATION means that you will try whether an intended corrective action works and VALIDATION means that you will confirm that it really works long term.
Verification of a corrective action should be done before or during its implementation. Obviously you will not implement an unworkable corrective action.
Validation of a corrective action should be done after the implementation of the corrective action to confirm its effectivity (that it really works) long term.