By the time I was a postdoc I felt as though I had developed my writing skills to the point that I knew what I was doing. I had written several papers and a thesis, and even though those were heavily edited by my PhD supervisor, I had learned a lot about my own style and writing.
It only took a single draft of my first paper as a postdoc to have that little illusion shredded. In less than 24 hours after handing what I thought was a solid draft of a manuscript to my PI, I got it back drenched in red. The carnage was horrific. I think a new Masters student had to leave the room to throw up. My first reaction was to wonder if I had inadvertently handed in an early copy, but alas, it was the new version. So, I sat down and picked through the remains.
Much of the damage was stylistic (though both excellent writers, my PhD and postdoc PIs have very different styles), but it forced me to think hard about my audience, the best way to communicate the message and finding my own style to accomplish the goal. I fixed it up and turned it around.
24 hours later*, another blood bath.
WTF? I thought I dealt with all the issues that came up from the first draft?
But the paper was changing, and with it, so was the "pitch". The subtle and not so subtle refinements along the way were absolutely critical in revealing the message and making it stick out over the layer of data below. This might have been the most useful skill (of many) that I learned as a postdoc - effective writing that goes beyond "getting the story out there" and gets into the realm of making people want to read it.
I haven't mastered this yet, but my postdoc set me in the right direction. It amuses me now to see the reaction I get from my own trainees when I had back drafts of their manuscripts. In the end, however, I think they appreciate the effort I'm putting in to both their drafts and to pushing them to be better writers. It's a craft we all need to hone at every opportunity, because most of the people that ever come across your work will do so in its written form.
*Yes, my postdoc supervisor was a fucking machine and dealing with text and getting things turned around.