Diversity in your workload is so important. I want to be a prolific creator, but also a sincere one. I've got several projects I'm passionate about, and I want everything to get the craft and care it deserves. I see some definite advantages on focusing on one project to its completion and then moving on to the next one. I'm just not sure that's the best way for me to approach creating.
I go through the entire creation process near daily with Public Education. I'm going to start working on the publishing aspects of the first collection of my webcomics as soon as school gets out for the year. I'm scripting a small science fiction story just for practice. I'm doing the rough layouts for the aforementioned new webcomic that'll be debuting later this year. Both of these stories being in conceptual phases also gives me the freedom to do lots of sketches to iron out the details and ideas within the story.
This means at any given time (at least free to devote to comics time) I can work on something I'm excited about. Don't want to script? Then I can work on layouts. Not really in a feel great about teaching mood? I can pick apart a new fantastical world I've created. Don't really want to write down a thing? Pop in some old Space Ghost episodes and try to learn something from a master as I doodle out opposums and snakes ad infinitum.
Timothy is taking the same approach with his art. Every night he's bouncing between the different parts of laying out Hellidays, to pencilling issue 5 of 3rd World, or working on his painting. There's work to be done to suit any mood.
You have to devote your entire head space to one project at a time. I try not to worry about any project but the one I'm sitting in front of at the moment. I'm a multitasker though, and its good to be able to always work on something I want to do. Regardless of how scattershot my attention may go.