Our client's approval workflow is 100% inboxes. At each stage of the approval workflow, the approval status drives which inbox the document appears in, and kicks off whatever approval work is required as a result. Query folders doesn't factor in at all. (Having said that, I'm looking at how we can use query folders right now, and can't make the examples in the documentation work. That's a separate discussion...)

Thank you for responding to the poll and your comments.

You are mentioning that query folders are very useful, could you describe in bit more detail what the use cases are?

While our content creators don't rely heavily on inboxes, they are essential for our editorial and validation specialists, who use them as their daily worklists. We would like the inbox functionality to continue to be available in future releases of Tridion Docs (with some enhancements, like email notification). We do not currently use query folders, but the functionality they offer is promising. We've only recently explored query folder functionality, but one drawback appears to be that only logical level metadata is available for query processing. Expanding query capability to a wider selection of metadata would be very useful. More comprehensive and straightforward documentation explaining the query folder functionality would be helpful as well.

We have never used inboxes nor query folders. We have a small team and it's not been necessary.

In my department, users in every role rely on inboxes to manage and transition their files. This includes information architects, authors, editors, graphic artists, and localization coordinators. Inboxes are crucial to managing our workflows. We do not use query folders.