If the e.g. scheduling code is messed up, and we find out 5 weeks in, then there is a lot of damage. We need to call all parties to review their schedules with

If the e.g. scheduling code is messed up, and we find out 5 weeks in, then there is a lot of damage. We need to call all parties to review their schedules with them. On the other hand if the code responsible for the styling of some menu is not working correct, the functionality may still work, and once we discover the bug we can simply fix it. > rarely do I hear of code that doesn't need to work correctly. So there are different grades. That's why I used the word maximum. The cost for these unit test should pay bank, even during the dev't phase, IHMO. There are often areas in a large code base for which this hold true, and often they can be identified as such beforehand; then writing these tests should be a priority.