Jack is the first strain I smoked, and I haven't seen it since. I've seen crosses of it, but never Jack Herer on it's own. Maybe it's because it was my first time smoking, but I swear that nug smelled different from any other nug I've smelled. Such a powerful, spicy aroma. I remember it cause I kept a 10 bag in my wallet, and the leather smelled like it for a good year.
I haven't been too interested in buying those stand alone terpenes, as my shash is strong smelling and tasting enough, but if there is a company who sells Jack Herer terps I'd buy em in a second.
This is totally off topic, maybe I should start a thread for distinct smelling/tasting strains. I know K-train and Jack are the two that come to mind for me.
As for getting things done, I don't notice a big difference between strains. What I do notice is that waiting to vape until I have completed the tasks I want to complete helps me get those things done because I want to vape. If I have projects or long work that I know I'll want to vape during I make sure to space it out, and to keep the doses low so that I don't get slow.