Oof, that is not true and frankly terrible advice. Most people who quit smoking try the 'just sometimes' approach and it leads back to the original smoking habit.

Framing it as self control problems is also a non starter. That shit is skillfully made addictive - if your outcomes are a high chance of chronic use and related illness or a low chance of occasional use and questionable benefits then the overall expected value is still deeply negative.

I have been smoking exactly one cigar or cigarette a month for over 10 years. I'm open to some hypothetical idea that one cigar a month leads to anything more than the slightest of additional risk, but I haven't found the data for it. Meanwhile it provides quite a bit of enjoyment.