Our team is utilizing a single space but we have different functional areas (FA) within our department so we've set it up so that each FA is a Project. We did this because most FAs have a bunch of tasks happening independent of the other FAs.

If we have a cross functional project, we've decided the best way to track all tasks related to the project is to name all tasks with the internal project name across all FAs. But that's not filterable, so we're tagging each one with the name of the task which gives us a great view of the overall project. This is redundant though. If we could filter on task name, we wouldn't need to use tags.