This is actually a perfect application of GTD. Most people don't realize how flexible GTD is, and feel like everythin must be well define, and have a time frame. It doesn't. You have the reviews for that. You have the "projects" list for that. You have "waiting for" for that.
"Spending time on 'creative job x'" is actually a perfectly good task name to add to your "project" list.
In your daily review, you scan the one you want to work and and you add the ones you feel like to your "next" list.
GTS itself must NEVER be applied as-is, and should be adapted to your line of work, rythm, life style and personnalité. And it's very good at it.
I guess I couldn't stomach the idea that GTD mandates dedicated review stages, while in Autofocus / FVP and in my own system review is a continuous process.
Ideally, I'd like to have the ability to do 'makeshift reviews' per-task, and on different timescales. For example, if I don't feel like doing Task X today, I'd defer it for 5 days, so its next review will happen in 5 days. But if there's another task I'll probably want to do tomorrow, I'd defer it to tomorrow, so I'll review it tomorrow.
On the other hand, I do seem to have a de-facto review stage. In the morning I usually go through my task list in Wunderlist (which I hate but use daily) and mark items I'd like to do today. But this is probably because Wunderlist doesn't offer a proper Defer / Hide Until ability that doesn't screw with tasks' due date.
(And I have a recurring task 'Review all items', a relic from a bygone era when I attempted to do GTD properly.)
This is exactly what I do - I have vague goals which I work towards with creative steps, eg 'take a couple of hours to think about what next with my open source project' and let my mind wander within that.
GTD deals explicitly with the creative process and how it helps by clearing your mind in an early chapter.
John Cleese talks about the importance of clearing your head before being creative here:
"Spending time on 'creative job x'" is actually a perfectly good task name to add to your "project" list.
In your daily review, you scan the one you want to work and and you add the ones you feel like to your "next" list.
GTS itself must NEVER be applied as-is, and should be adapted to your line of work, rythm, life style and personnalité. And it's very good at it.