I would say that while not off-topic, productivity is toeing the line and likely better at Productivity.SE
"Where does it have more overlap?"
Is there going to be be more overlap between workplace productivity and non-workplace productivity questions, or workplace productivity vs. workplace unrelated to productivity questions?
Here are the top voted questions over at productivity:
- How do I get myself out of bed in the morning?
- How do I deal with distractions when working on a computer?
- Does listening to music help or hurt productivity?
- How can I improve reading speed and comprehension?
- Early birds vs. night owls: what does research have to say?
- How do I make myself stop doing addictive activity?
Here are the top voted questions here:
- How should I deal with an employee who has slept with my wife?
- Is it rude to leave an interview early if you have already made your decision?
- How can I overcome "years of experience" requirements when applying to positions?
- How can I prepare for getting hit by a bus?
- How can I ask my interviewers for feedback following an interview?
- How can I tell people to get to the point?
An expert on workplace productivity would be able to answer likely 5/6 questions on productivity. A productivity expert would likely be able to answer 0/6 (maybe 1/6 if you consider having people getting to the point to be productive) over here. So the experts will congregate there, which makes this sort of question more likely to get an expert answer there.
Borderline Off-Topic Aspects
As our Help Center says:
"How do I learn to be a..." / "How do I perform the job of a ..."
Questions should be about problems you are encountering or have encountered in the workplace, and not the learning/applying of specific job functions.
While 'getting stuff done' isn't exactly a specific job function, it certainly does toe the line. For instance, "How can I be more productive at managing inventory levels?" or "How can I increase productivity of bug reporting?" are certainly things that strike me more as "How do I do my job?"
Productivity as a Potential (but not only) Solution
Think of a productivity question like this:
"I just got a horrible performance review because my boss says I don't finish tasks on time. I am working 60 hour weeks but none of my coworkers are having the same issue. How do I become more productive at the workplace?"
I think the Workplace approach would be to figure out what the fundamental issue behind the poor review was (was it poor communication? was it failure to report delays in a timely fashion? was it actually just poor workplace efficiency?), and then to find a way to solve that problem (explaining how to report effectively, or how to deal with delays in a project, or how to explain an underestimate to a boss, etc.). One of the potential solutions would be become more efficient in X or Y or Z, but how to become more efficient in X, Y, or Z would be better suited for productivity.SE
I say we burninate the tag, and migrate the questions (when good questions) to productivity instead.