The software development approach often need to change to accommodate the code fix, which can in turn bump back other code changes. So not only is the bug going to cost more to fix as it moves through a second round of SDLC, but a different code change could be delayed, which adds cost to that code change as well. To illustrate: if a bug is found in the requirements-gathering phase, the cost could be $100. If we don’t find that bug until the QA testing phase, then the cost could be $1500. If it’s not found until production, the cost could be $10,000. And if the bug is never found, it could be secretly costing the company money and no one could be the wiser.