It's hard to say what "heavy/investigative reporting" means in the context of Buzzfeed. I don't expect we're talking multi-month government corruption investigative journalism. But a couple of weeks to a month is still pretty reasonable for a 6000 word story that requires setting up and conducting a bunch of interviews and doing other research.
My rule of thumb has generally been about 1000 words a day not counting any heavy research so your numbers seem pretty reasonable.
Furthermore, freelancers rarely have a fully booked schedule and they need to spend time on tasks like prospecting for new work.
In a prior life, we'd get paid very nicely on a daily basis for consulting and other custom/semi-custom work. But the reality was that we weren't actually on the clock very much and spent a lot of time maintaining the knowledge base that let us do those jobs when they came along.
My tech writing was pretty lucrative since I was pretty fluent in the content. I spent more time coordinating review units, generating good photos (when PR provided imagery wasn't suitable), and dealing with editors. I could write 2-3k words in a day after having mentally written it in my mind over the previous weak. If the subject matter was something that I was unfamiliar with, the time investment to be able to discuss it consumed more. I was always better when I procrastinated anyways; pressure would require me to distill my writing down to the core essentials.
That reflects most of my experiences. I usually thought in terms of an average "production day" which was usually about half of an actual day writing with the rest of the day researching, "researching," and doing various client work.
Of course, it varied. We often talked in terms of "memo grade" writeups for things like summarizing an advisory day which fell more in the 2K words/day range. On the other hand, I've spent the better part of a day trying to figure how to get into a piece and then ending up throwing away the whole introduction the next day.
"throwing away the whole introduction the next day."
Too true! My wife always talked about how much I was paid per word; not understanding that I might write 5000 words for a 2k article. I got much better over time, but that was due to honing my skills at procrastination more than anything else.
My rule of thumb has generally been about 1000 words a day not counting any heavy research so your numbers seem pretty reasonable.
Furthermore, freelancers rarely have a fully booked schedule and they need to spend time on tasks like prospecting for new work.
In a prior life, we'd get paid very nicely on a daily basis for consulting and other custom/semi-custom work. But the reality was that we weren't actually on the clock very much and spent a lot of time maintaining the knowledge base that let us do those jobs when they came along.