The 'Automatic distribution post' costs 1000 tech points and uses the current building model, and works as I described above. Cost 250 tech points but a little less in resources since half the routes). It works like the old distribution post (but half as many routes). The new 'distribution post' would be a smaller (3x3?) building that has 5 trade routes. No more micromanaging, you just set what you want each district to have, and any district with a distribution post tries to move their resources out to fill holes in other districts. It sends any planks over 300 to your new district if it has less than 50, etc. It sends any logs over 1000 to your new district if it has less than 300. Without setting up anything, your distribution post takes any water over 1000 and sends it to your new district if it has under 200. Your old district has water desired of 1000, all foods at 500, logs at 1000, planks at 300, etc. You know how warehouses have automatic balancing? What if distribution posts automatically moved 'excess' resources out of districts to districts that were 'short'? You create a new district and set your desired water to 200, logs to 300, planks to 50, each food to 100, etc. OK, I'm going to give the short solution, and then my preferred solution.

Timberborn floodgates