Expecting failure is essential in design and testing of designs/models, as well as in international development programs.
International development
A difficulty of admitting failure (essential to good development practice and achieving improvements in aid effectiveness) is the fear that donors and superiors will be unhappy if they know about the failure, and funding or one's job will be lost. It is important to ensure that it is safe to admit failure.
Realistic expectations by aid donors help - expect that failures will be frequent, especially when innovating. This is not a waste, provided that learning occurs and lessons are shared widely. This is just part of what it takes to innovate and be effective.
Testing design - products and programs
To be sure that a design or a program does what is intended and does it well, extensive testing is generally advisable. Part of effective testing is to expect failure and look for it with determination. Adjust the design, and repeat. Get others with a critical eye to do their own testing. When you can no longer find an error, it doesn't mean it's now perfect. You still need to "expect failure" in terms of looking out for problems and ways to improve - however you can be satisfied that you've already improved the design, and it has a better chance of working well.
