Have a progression skill tree, where the more you work on something, the better you get, exemple, in a turn you can perform "x" amout of actions, you choose to help out on the lumbermills, every time you go there you gain woodcutting exp, when you lvlup the passive woodcutting income increases, the same on the mines and the efectiveness of your armies on the battlefield, having a percentage boost on there damge, defence and even the amout of troop you can comand at once.