I am a fast writer. I also have a scholarly career already up and running. I have a scholarly base, self-confidence, time... While these tricks are designed to benefit everyone, they are also a way of keeping myself motivated.
I can write a 6,000-word article in 12-24 days of writing (assuming 250-500 words a day) for 2 to 3 hours. Figure in another 3-6 days of revision. So 15-27 days. These days willl usually fall into 1-3 separate months, not necessarily consecutive. Four months or more brings about a dissipation of energy.
So suppose you were twice as slow as I was. We're still talking 30-60 days. Those might have to fit in 2-5 months. You can still write the equivalent of 2 articles a year, which is quite respectable. Imagine coming up for full professor after 8 years and having 16 articles or the equivalent in books / book chapters.
If you don't feel smart or fast, you can be always be more regular and disciplined. Even if you are smart and a fast worker, the consistency of effort will be what determined what actually gets done.