The general version of a problem being NP-complete doesn't mean that cases of practical interest are all necessarily intractable. In the case of SAT, for instan

The general version of a problem being NP-complete doesn't mean that cases of practical interest are all necessarily intractable. In the case of SAT, for instance, there are also ways for the humans to give the solver an easier problem to solve in many cases, like adding extra clauses to guide the solver away from useless parts of the search space.