Comment by layer8

A better formulation of DRY is SPOT (Single Point Of Truth). Definitions (code, data) that represent the same “truth”, i.e. when one changes all have to change to represent a consistent truth, should be reduced to a single definition. For example, if there is a rule that pizzas need at least one topping, there should only be a single place where that condition is expressed, so that when the rule changes, it isn’t just changed in one place but not the others. Another example is when fixing a bug, you don’t want to have to fix it in multiple places (or, more likely, neglect to fix it in the other places).