I try to work on different parts of the project at different times. If I feel burned out from drawing art for it, I'll write scripts or come up with ideas/concepts. If my brain runs dry, then I might try and draw some of those concepts or work on pages for upcoming episodes. I like to give myself the ability to exercise different creative parts of my brain so that I can have a bit of variety. If I was constantly drawing and writing at the same time, I'd probably burn myself out.
I also have a creative job so in a way, I guess that's a creative break for 8 hours a day. The downside is that sometimes I just have to take a break from everything for a few evenings because it's like a creative overload for my brain and/or my wrist hurts.
On my off days, I like to think the act of me "making" anything is me being creative. Making food, taking pictures, etc... sometimes I go as far as telling myself, "I'm making my apartment clean, therefore I am creating." 