I've undertaken several sustained projects. Some are ongoing, some I have completed.
1. My undergraduate thesis was the result of about fifteen months of work. I wrote three other article-length pieces in my undergrad, but they weren't very impressive and I don't like to talk about them.
2. I have written a set of advanced macroeconomics lecture notes, to the tune of about 150 pages. They'll be used to supplement our graduate macro course next year. They'll be finished in about a month, and will represent basically everything I know about macroeconomics. I'm more than a little proud of them.
3. I'm starting a new writing regimen this year, which should turn out fruitful. I'm allocating 80 blocks of time this semester to writing. They could be as short as 30 minutes or as long as 3 hours, but I am committed to writing for those intervals: five times per week, for sixteen weeks. I hope to complete one standard-length (40 paragraph) academic article in that time. Wash, rinse, repeat 3 times per year for the next four years.
Three projects per year. Some won't pan out, but I'm hoping that at least three of them will.
The result of the first such project is a little paper on oil and the macroeconomy.