Both papers touched upon the effect of smoking on life expectancy and how the trends differ by sex. Christensen et. al mentions that life expectancy stagnation is observed in Denmark that is mostly related to smoking patterns, and that this stagnation is more pronounced among women. This note is in the agreement with the smoking--life expectancy trends recorded in Preston et al. in the U.S. -- they observe no gain in female life expectancy as a result of smoking reductions between 2010 and 2020. Preston et al. explain this pattern by the fact that the heaviest smoking cohort of women was reaching the prime age of dying in that time interval. I think that this observed modification of the effect of historical smoking patterns on the expected life expectancy by sex highlights the importance of disaggregation of the data. Particular groups of people may adopt different behavioral patterns and depending on the size of a group this might affect the outcome of interest in the overall studied population (e.g. life expectancy in this case).
It was also interesting to see how Preston et al. estimated the effect of smoking by using the death rate of lung cancer as an indicator. I think that the value of this indicator might decrease with time due to decrease in smoking in a studied population. It has been noted, for example, that the proportion of oropharyngeal cancers due to smoking has substantially decreased and the proportion of these cancers due to other reasons (e.g. HPV infection) has increased. I would expect a similar trend for the lung cancer. And there are some populations that have a high rate of lung cancer and are never-smokers (Incidence of Lung Cancer Among Never-Smoking Asian American, Native Hawaiian, and Pacific Islander Females).
Personally, I really liked this idea mentioned by Christensen et. al that future generations might work fewer hours per week because more work will be done by older people who will remain healthy due to improvements in medical advancements and disability-free years. So, overall the amount of work in a person's lifetime won't change, but it will be distributed over a longer period of time. Looks promising!