Do all scientists use the scientific method?
Anyone who does problem solving uses some form of the scientific method.
The typical approach includes
Identifying a Problem
Researching the Information
Stating a Hypothesis (Possible Solution)
Testing the Hypothesis
Analysis of the Data
Stating a Conclusion
Publishing the Result
Depending upon the parameters of the problem and the executed outcomes desired some or all of these steps can be used in the search for answers. Whether an individual is trying to find a cure for cancer or determining which school is the best college to attend the scientific method can be used as a means of organizing the process.
I hope this was helpful.