What Enerjy found was that routines with CCNs of 1 through 25 did not follow the expected result that greater CCN correlates to greater probability of defects.Not so. What Enerjy say their result concerns is:
the correlation of Cyclomatic Complexity (CC) values at the file level [...] against the probability of faults being found in those files [...]). [my emphasis]It's interesting all by itself that there's a sweet spot for the total complexity of the code in a file, which for Java pretty much means all the methods in a class. However, Binstock suggests that
[...] for most code you write, CCN does not tell you anything useful about the likelihood of your code’s quality.Which it might not if you only think about it as a number attached to a single method, and that there are no methods of high complexity. But there are methods of high complexity—and they are likely to put your class/file into the regime where complexity is shown to correlate with the likelyhood of defects. Watch out for them.