What is the "golden ratio" of blended coffee

There were strange rules for making mixed coffee a long time ago, one of which was called the "mixed golden ratio". It is mentioned that as long as the correct combination of Columbia Madeleine (Medellin), Mocha. Matali, Santos, Brazil, can make a harmonious taste.

Another rule is to add a supporting role that emits high-quality bitterness, Java Robusta, to the coffee at a rate of 20% to 30%. It can make the coffee taste better, but now it seems that I don't know whether to say ignorant or casual.

There are also a set of rules for making "sour mixed coffee" or "bitter mixed coffee".

Sour mixed coffee: 50% mocha + 30% Colombia + 20% Brazil

Bitter mixed coffee: 30% Java Robusta + 30% Brazil Santos + 20% Colombian Mandarin + 20% Mokajara.

These rules look quite simple now, because when they came into being, the coffee industry was not yet mature. The knowledge related to raw beans and baking techniques are still in an immature state, so blindly believe that Robusta equals good bitterness and mocha equals sour taste.

Although there is some truth in the proportion of these rules in some ways, the effect of the degree of baking on taste is far greater than the difference between place of origin and place of origin.

[so, when you want to make your own cup of mixed coffee, don't blindly believe these rules.]