The Offer, The Target Client. When and Which to Tweak.

Is it ok to determine we have a bad offer (ZERO Yes’s) and then change the offer and then offer to the same (previous NO) people? That would tell us if it really was the offer?
I know there is not an answer, however at the risk of asking….how much do you invest (time /resources) in cultivating a “not yet” ? At some point, you just gotta call the game, right?