To me, the most important "learning outcome" from reading Henry is a healthly skepticism. It reminds us much of what we read about photographic technique and materials has little in the way of evidence to back it up. And as Stephen has said many times, even when we are presented with data it is important to be given information on the testing procedures, otherwise it is difficult to conclude anything. Sometimes you read an article in a magazine and it looks really sound because is has tables and charts and curves. But what if there were all sorts of errors or sources of error, mistakes etc in the test? As we know there are many variables to manage, and as I've come to learn, designing a proper photographic test is not so easy.