When upgrading buildings or customizing El Presidente, you are offered a couple of options that affect production by a certain percentage, for example
+20% Production. You know that you will somehow get more output from your buildings but the actual effect/mechanic is not perfectly clear.
Suppose I have 100 units of raw material that convert to 100 units of finished goods in one cycle. Does a
+20% Production bonus mean that
I will receive 120 units of finished products out of 100 units of raw material (better input/output ratio)
I will receive 120 units of finished products but consume 120 units of raw material (same input/output ratio, faster rate).
In case you are getting more output for the same input, it's almost always a good idea to purchase factory upgrades but otherwise it's only useful if you have tons of stock or understaffed buildings.