In my experience of writing articles and reviews for different publications, I didn’t follow a job description and I did my writing in a time frame that suited me. I’m not a career writer. There were no specified expectations of me, so I got experience in freelance writing as I wrote articles and reviewed movies I wanted to. I learnt that focusing on one writing opportunity at a time would have been better because I could pour all my energies into it. But I felt that wasn’t enough. I needed more. There may be factors preventing one from focusing. One may feel he missed out on something more in writing if focusing only on one publisher. But one can always move onto another publisher when satisfied with writing for the publisher you’re with. Move onto the next, if the opportunity presents. Or purposely stay with the tried and true.