Left, right, right, left, right... right? Nope, I'm lost... lemme see... left, right left, left...
Ever "lost" a file only a week after having created it? It's in Documents > Clients > UK > nah, not there, click, click... in UK > Clients > Correspondence... not... let's try Spotlight... hmm, what was that file name again?
Pretty useless those tree structures. That's why the thingamy does away with them altogether.
And the alternative? Multiple tags filtering.
Tags everywhere representing anything adding up to a real knowledge-bearing-name-space.
Choose "UK GAAP, P&L, Expenses, Production cost" and see only the accounts for that. De-highlight UK and highlight US and see the corresponding selection now for US GAAP.
Invoke a report and choose "Contacts, US, Suppliers" and see Mike, Bob and Ted, de-highlight US and highlight France and immediately get Pierre, François and Michel on your screen.
In a task to choose co-worker set task to give operator / assignee all employees - select the tags "C++, German speaking, Beer drinker" and see the list shrink.
No hierarchy, tree structures, no folders. Efficient browsing of all data when navigating, reporting, working, selecting...
Why not go all the way and do an operating system with no file structure and no applications?
Next step, a bit later, just have to refine this stuff a bit first... :)