When you're under the gun (and even when you're not), one great way to waste time is to try to get everything perfect the first time around. Phrasing, flow, punctuation, even spelling and grammar. It's hard to be productive and prolific when you do that.
Instead, you should really try to get the first draft out as quickly as possible. Holes and all. From there, edit, rewrite, and restructure. By doing that, you're not only pushing yourself down the road to completing your piece, but also removing some of the stress that could cause you to butt up against a block.
I admit it's not an easy habit to get into, but once you do you'll be able to complete articles, essays, or whatever it is that you're writing in record time.