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.
The efficacy of bandying threats of going to hell met its match in the Civil War.
I love the efficacy, but there has to be a less extreme way.
To the efficacy and permanency of your union a government for the whole is indispensable.
He no more believes in the efficacy of soap than in the efficacy of a good reputation.
He is a firm believer in the efficacy of brandy to keep out the cold.
All races have uttered this prayer, apparently with a firm belief in its efficacy.
He says that, "Like the immortal Washington, he believed in the efficacy of prayer."
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.