I kept a pint of ice cream in the freezer and a bag of chips in the cupboard. The reasoning for me was: I'll never impulse buy snacks while at the store, because I already have it at home.
And if I haven't eaten out of my pint of ice cream, then I haven't eaten any ice cream.
It's like knowing you have these traps to avoid, but if you just keep one very close, that's the only one you need to consider, and then all the other ones disappear. It's definitely a focus thing for me, don't know if it was the same for your dad.
Love that roundup of this technique. Coincidentally enough my dad also used this same aid to quit smoking. I saw some slight sense but never enough to unpack it myself.