It would be very easy to implement and help some great deal.
At the moment when you have a lot of countries you have to go manually one by one and select what auto production they would have.
Normally we all select one like infantry , militias or marines.
But this takes much time and instead if implement you would click on select all countries you have and a drop down box would appear of all the possible units you can build and then you would select your unit and it would be made to auto produce in all your cities or countries that you have when you click execute all or if you have auto production checkbox clicked on.
Edit: i saw it has been proposed already by Chess and others after i already made thread bla