Just be careful. Often there are goals other than efficiency. If you get the dishwasher unloaded while cooking - but burn the meal that was a loss. you might be able to do something else while unloading the dishwasher if your sort order is less effient. Or sometimes sorting is less efficent as there isn't enough to do as to make up for the overhead of sorting.

Good point, thats how I feel about to do lists most of the time.

I think the key insight you make is recognizing that attempting to do two things at the same time is asking for disaster. Concurrency in my experience is all about rhythm and timing… something humans in their default state are notoriously bad at ie without training and practice. The best approach in my experience is doing one thing at a time with focus and conviction until completion, then move on to the next thing. If concurrency is desired then understanding duration and prioritizing items via dependencies is of utmost prudence. But paraphrasing Michel de Montaigne… something something about something