Quick minor process point here (which I know Dan knows, but just didn't spell out in this case): Experimental work done during your "10% time" does not need to be prioritized by any product owner. For that work, it might make sense to track it in phab, but it might not, so use your judgment there, or chat with your product owner about it.

Within the few months that Discovery has been officially supporting "10% time" projects, they have already produced some really good work, and have been turned into production features on multiple occasions.

Experimental work that isn't part of the 10% absolutely needs to be phabbed, and then prioritized by the PO.

Kevin