6393-2 Why was development of such a variety of powder flow test methods inevitable ?

6393-2 Why was development of such a variety of powder flow test methods inevitable ?

The widespread use of powders in the pharmaceutical industry has generated a variety of methods for characterising powder flow. Not surprisingly, scores of references appear in the pharmaceutical literature, attempting to correlate the various measures of powder flow to manufacturing properties. The development of such a variety of test methods was inevitable; powder behavior is multifaceted and thus complicates the effort to characterise powder flow.

Why was development of such a variety of powder flow test methods inevitable ?

HMKFlow 6393 PT1000 Powder Characteristics Tester