A lifelong chain smoker will smoke a cigarette in 1-2 minutes and light up another. 3-5 minutes is a relaxed casual smoke. Cigarettes were modified a decade or so ago to ensure that they go out quickly if not actively smoked. It's not even possible anymore to keep a cigarette burning for long enough for it to take 10 minutes.

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.

Lucille Ball's voice changed dramatically over the course of the 6yr show from heavy smoking. Their show was sponsored by cigarette companies and she used to hand out cigarettes on a platter to guest when they came over to her house.