Agreed realistically there will always things that limit your productive time, and that's normal, although management will try to push against that. The question is from a company policy point of view. E.g. new policy "Employees are allowed 3 smoke breaks a day , or they may use an e-sig at their desk."

There are studies around showing that even a few minutes walk can increase creativity. So it is actually possible that smokers that are going out to smoke are actually more creative that their sitting counterparts.

Here for example : http://well.blogs.nytimes.com/2014/04/30/want-to-be-more-cre... but there are likely more serious link around.