WCCA is the best method to ensure a Rugged product design.
Worst Case Circuit Anaysis and Schematic Design are often done at the same time.   For WCCA the designer ensures that under all use cases (and all conceivable and realistic misuse cases) the product will perform as desired.
WCCA looks at temperature variations, initial tolerances, humidity effects, elevation, aging, and other sources of tolerance and noise.   Under the worst-case stack-up condition, the designer ensures the circuit is - as it's called in the industry - "bulletproof".
An example could be selecting the proper resistor value.   WCCA might prove that a 1% resistor value of between 500 Ohms and 25,000 Ohms will provide the same end result.   In this case, the proper decision is to choose the most cost effective part based on factors such as economy of scale.