Neither represents a good argument for the efficacy of the insurance.
One of the reasons for the German collapse on the home front was the efficacy of the blockade.
Certainly one can disagree about the utility or efficacy of BDS as a tactic.
1520s, from Latin efficacia "efficacy, efficiency," from efficax (genitive efficacis) "powerful, effective," from stem of efficere "work out, accomplish" (see effect). Earlier in same sense was efficace (c.1200), from Old French eficace (14c.), from Latin efficacia; also efficacite (early 15c.), from Latin efficacitatem.