Here in Canada, cigarettes do come in various lengths. There are one or two 120mm brands (the American import brand More is an example), some 100mm brands (Benson & Hedges), many King Size brands at 85mm, and many at what we call Regular length, or 70mm.
Despite the fact that most Regular length brands have a King Size equivalent (DuMaurier, Export A, and Number 7 are some examples), most King smokers of my acquaintance stick with Kings, and most Regular smokers stick with Regulars. The time available to smoke has little to do with it (in other words, a King smoker wouldn’t smoke a Regular if they only had five minutes); rather, it seems to be more of a personal preference for the brand and size.
Your idea might work, but given the brand and size loyalty I see among my smoking friends, I wouldn’t bank on it. Especially with smoking as unpopular as it is today, I think a lot more research would be needed before you were sure that your idea was worth taking a chance on.