That used to happen to me and then toward the end of my addiction I only did heroin but if I slipped up a little I would say screw it and do a massive amount of heroin. Basically same thought process of thinking "hey I slipped up might as well go all the way"
The best way to avoid these massive slip ups and free for alls to stay away from all substances and fully immerse yourself into our recovery. Whenever you have a craving think of your children and how much they deserve and need you to be sober. I know a couple people that carry around a picture of their children or family to fight urges and stay motivated.