One of the ideas I totally disagree with people who advocate Test Automation is their claims of Automation tools being able to run tests much faster as compared to Human Testers. But my question is why do you want to compare an Automation Tool to a Human Tester? How did this comparison even arise?
According to me, a Tool can be some device which may be used to facilitate or aid in performing manual tasks. So, why should speed of Human is compared to speed of an aid he uses?
I remember using Scientific Calculators in my Engineering Degree. The calculator was used as a tool aiding in calculations. Few formulae could also be fed or stored into it. But, I have never heard anybody saying that the calculators should be replacing the engineers as it is able to execute the calculations much faster than humans. But what good is a calculator without humans? It cannot perform any task on its own, it cannot have logic, it cannot think. But it is very useful if an Engineer who has a calculator knows what benefits he can derive from it and knows when, how and where to use it and get maximum benefits from it.
We should understand that the purpose of a Calculator or a Test Automation tool is to aid humans in doing their tasks in a better way. This would allow humans to spend their time more judiciously on more important things in what he is good at and allowing the tools to do tasks for which they were specifically made for. Even the Test Automation is a heavily human intensive task. So a Test Automation tool can execute tests much faster than humans, but it cannot do anything by itself. The Test Design has to be done by humans, identifying tests for automation, creating automation scripts, maintaining automation scripts, identifying the comparison criteria (pass/fail criteria) and investigating the issues if any mis-match is found in the Test execution results, all these activities has to be done by human testers.
So, next time when you hear someone speaking about Test Automation tools being able to execute tests faster than Human Testers, make him understand why he should not be doing and talking about such comparisons.