Thanks for brining up a great issue. Being somewhat a productivity nerd myself at some point I observed what really made me go work at pace. My take on this is that despite Holacracy being a "super autonomous", "my domain" type of arrangement, it is basically community/collbaration based so I would focus on this aspect.
So my goal would be to set-up a kind of "peer-review" system for the work that basically would shorten the feedback loops and give context who is waiting for what and why it is important.
For me, the most important thing is the keep the momentum and it's either deadlines or needs of other people or the project (a.k.a. something bigger).
I come from Game Development background and we often get stuck with "feature creep" and "it's done when it's done mindset". Sometimes when we get stuck we do "game jams". They usually last 1-3 days and the aim is to produce "something" to get unstuck.
If you have a circle responsible for a specific project maybe you can alter your circle's tacticals to more of a "sprint like" reviews once per month or so as a starting point and then see if it helps the creatives or not.