The obvious problem is that you would get a different length each time. You could never be sure where to cut the board. Some certification tests today are like this tape measure unreliable, producing inconsistent scoring. Of course, this makes it impossible to use such tests to make good certification decisions.
Reliability is one of only two necessary characteristics of a good test.
Simply defined, reliability refers to the ability of the test to measure accurately each time it is used, like a typical tape measure. For example, under similar conditions it should provide similar scores when testing a person more than once or two persons of equivalent ability. Any basic textbook on testing and psychometrics provides several accepted methods to calculate reliability. Without following the proper steps to build a good exam, all IT certification programs are at risk and would likely produce tests that are unreliable. In addition, the IT certification phenomenon over the past few years has encouraged the development of very creative test designs, particularly performance-based tests, those that use labs or software, subjective scoring or take several hours to complete.