also, unlike the case of an AI where you have to avoid crippling it, lest it becomes pointless to build it in the first place, using unbreakable wows as a punishment for grand crimes against humanity means that the restraints can be nearly abritarily harsh. The people writing the wows have no need to preserve the decision space they leave their victim or respect their autonomy. TLDR: Voldemort would not be able to spend decades thinking of ways around the wow, because doing so would violate any sensibly formulated wow. (stray toughts, sure, you have to permit that, or the wow kills in a day. Sitting down and working at it? No.)