I have always considered it an actors job to ensure their hands or cigarette or whatever are in the same position when they hit the same word during multiple takes.
It's never going to be perfect or identical. Actors' #1 job is to give an emotionally believable, powerful performance. A thousand little details are different in every take, and your movements will change to reflect what is authentic in the moment. In fact, editors want emotional variety so that they have more options in assembling the scene.
Yes, things are blocked ahead of time. You'll stand up at the same moment, you'll stop walking at a particular mark. But there are limits, especially with things like hands and cigarettes. If you look for continuity errors around those, you'll find them everywhere. Actors, directors and editors have more important things to worry about.
