When using the free version of Google Tag Manager you will get only three workspaces, the default workspace, and two extra. This can be annoying when you have multiple changes pending or are working with multiple people on one container and the workspaces are all occupied.
Sometimes a workspace keeps open for weeks, blocking other changes.

Get more workspaces

Here is a trick to minimize this situation.
Workspaces are limited within one container, but containers are unlimited and free!
If you create multiple test-containers, every test-container contains 3 extra workspaces to use.
These containers can be injected on your website with the chrome plugin TagManagerInjector.

Now if you start a workspace, first determine if this is a change that maybe takes longer than a day or when you need to test and try some stuff that can last some days.
Now use your test-container and inject the container on the website.
When you are done, just copy it to your website-container and publish it.

You will keep your website-container GTM workspaces unoccupied, try to have only an empty default workspace at the end of every day 🙂