My step-father’s parents smoked a carton a day. Each. They started smoking before breakfast and stopped just before sleep. Their trailer home had a 2-3’ cloud of haze below the ceiling and every surface was sticky. I’m not how many years they smoked like that, but probably decades.

As a kid, I could not breathe in there. This would have been late 70s. No way they could have afforded that habit at today’s prices.

John Wayne is said to have chain-smoked 5-7 packs a day? If you can smoke a cigarette every ~30 mins, that's 2/hour (actually about 1.5 packs/day), but if a cigarette takes 10 minutes to smoke and you chain-smoke, that's 6/hour (4.5 packs/day). So it's doable but John Wayne was significantly out of breath the last 10+ years of his life, perhaps from having an entire lung removed.

I don't know how they did it but 50 years ago some people did seem to smoke non-stop. Of course they were still an exception. Of course when they cigarettes were dirt cheap you could let atleast a few burn up with just a puff or two off it also. These days they are so expensive from taxes that setting it down and breathing for a second instead of smoking can feel like burning money.