As my Chemistry Prof often said, “keep it simple, stupid”.
For cross team ownership, much depends on the team members’ relative familiarity with the Source Data, any ETL work to Tableau, any Tableau Calculations, and any “Hacks” used to create the workbook. If your pool of users is relatively unfamiliar with any of the above for a given workbook, you’ll want to have documentation built into the metadata, typically in the form of comments in calcs, commented metadata, and extensive, routine knowledge share.
A healthy analytics culture will encourage knowledge share as part of their routine, so that any new developments on the topics above are well-circulated amongst the pool of analysts. If you have a well-trained team, then shared ownership isn’t too daunting.
From a management perspective, reward not just the brightest, but the brightest that share and educate others. Those are the folks that you safe from the lottery, (aka the bus), problem.
When it comes to organizing dashboards in the form of “projects” and “workbooks”, I think the former is built on either need-to-access or subject matter and functional area, possibly both. The perspective on openness within the culture of the company will play a big role in informing the access perspective. That said, it’s also important to keep permissions and access paradigms as simple as possible. Most organizations generally tend to over-complicate permissions and access, which leads to reduced productivity, confusion, frustration; all bad things. Tableau is very open and leads by example on that front.
For workbooks, I prefer to keep them simple; there are other, better ways to merge content besides putting lots of different content into one monster workbook. You can run meetings from a handful of links within the meeting agenda each going to multiple simple workbooks, to keep things straightforward, organized, coherent.
This approach allows tags and search on Tableau Server to stay especially meaningful. For an example of what not to do, if you tag a single monster workbook with every subject under the sun, because it has every single subject under the sun, then it dilutes the effectiveness of tags as a search index and people are easily lost and can’t find their content effectively.