# Agility Requires Safety: Engineering, Technical | Y Combinator  ## Metadata - Author: [[ycombinator.com]] - Full Title: Agility Requires Safety: Engineering, Technical | Y Combinator - Category: #articles - URL: https://www.ycombinator.com/library/55-agility-requires-safety ## Highlights - If you're building a prototype that you'll most likely throw away in a week, the cost of bugs is low, so it may not pay off to invest in tests. On the other hand, if you're building a payment processing system, the cost of bugs is very high: You don't want to charge a customer's credit card twice, or for the wrong amount ([View Highlight](https://instapaper.com/read/1513562021/19967673))