Just read your post. I think this is a good starting point but no method of organizing is a one size fits all approach.
I still prefer to have events, usually named after the location I filmed at (personal preference), and will use most of the default smart collections. Keywords can be a beast and too many of them creates clutter which is unnecessary.
My approach for smart collections:
I would have one called Select-O-Matic, where I can choose on how things are sorted, using the same approach as outlined in the post.
I would use collections for graphics, interviews, titles, sound effects, music and things like that. Roles would be used to narrow down what I am looking for.
As pointed out, while this would be my personal approach everyone should use what is best for them. The last thing I want to do is tell people how to handle their workflow. I welcome feedback.