So to the addict who is hooked on crack, a little bit is not bad? Or to the sex addict who is hiding his affair, a secret rendezvous (with someone not his wife) is not bad?
Is Christ wrong that a 'little leaven spoils the whole lump'?
No, there are no halfway measures to deal with temptations and lusts. Halfway measures are total failures with both of these and are just as deadly.
Nothing I wrote supports that. For an addict, any indulgence of his/her addiction is an overindulgence, because by the very nature of addiction they are placing the object of their desire at the center of their life instead of God.
What you fail to understand, apparently, is that not all our desires are lusts until we distort them into being such (typically when we fail to follow Scriptural instructions). I would not accuse you of gluttony if you simply ate breakfast today. Did you indulge a lust, or did you merely satisfy a God given hunger? Now if you had 12 blueberry pancakes, a pound of bacon and washed it down with a gallon of cider, you probably drifted into gluttony territory.
A crack addict or alcoholic who has only, "a little bit," is placing a false god before God, and is therefore, not complying with the intent of God's instructions. A sex addict who strays outside his/her marital vows (or arguably abuses the gift within the context of their marriage) is similarly abusing the God given gift of sexual desire.