Although I’m working hard on my third novel (in between packing boxes!), and I think it’s important to focus on your main work, I’ve found it useful to tackle other, smaller projects. It stops you getting fixated, helps you draw breath mentally and makes you use different writing muscles in your head. You use different style, voice, vocabulary and register. I find the general effect is to refresh my writing as well as my dedication.
I recently sent off an article about why I love my bit of France for the French Magazine, a lifestyle mag, and also completed a diary for the Mass Observation Archive for 12 March. Two completely different styles from my romantic adventure novels and, almost as important, from each other.
As a side note, I used the MassObs Archive when I was researching material for my MA, so I was more than happy to contribute something in return.