The wage class is the umbrella for all wage code related information. Normally, the wage class is the same as payroll system. This means you probably will use only one wage class as long as only one payroll system is connected. You must define one wage class for each payroll system involved. The reason for this is that each payroll system has its own set of wage codes.
Even if you don't transfer time and attendance, or expense information to payroll, you need to define one wage class. The wage class is mandatory information.
Several wage classes can be used also when there is only one payroll system present. This is when you would like to keep wage code related information such as working hour schedules, or work hour rules, separated for different kind of employees. For instance, in your organization you have divided the responsibility for this information on two teams, one for category A (e.g., blue collar). and one for category B (e.g., white collar). However, this require you to keep double sets of the same wage codes.