This is all pedantic. The point is that you can chain smoke quite a lot if you're dedicated. I've never met anyone who smoked more than two packs a day regularly or maybe three on a crazy night out of drinking and smoking. 4-5 is crazy.
He'd go through something like 80 Embassy back then, a day. He gave up in 1984ish and is still trundling along. His Dad died at age 60 of lung cancer.
I gave up about eight years ago after 30 odd years at roughly 20 a day. I definitely did some damage and will eventually have to find out how much. I don't have a near permanent cough and at least five major bouts of 'flu per year anymore. I did have a short bout of Covid in 2021 and I suspect it might have been really nasty if I was still a smoker then.