* University policies: Each university and even each department within a university will have its own rules about course loads. Some might have a minimum and maximum number of credit hours, while others might have restrictions based on the type of courses or your program.
* Your program of study: A demanding program like engineering or medicine might have a prescribed course load that leaves little flexibility, while a humanities program might offer more freedom.
* Your own capabilities: Some students thrive on a heavy course load, while others find it overwhelming. It's crucial to be realistic about your own capacity to handle the workload.
There's no single answer. You could take as few as one or two subjects in some circumstances (e.g., part-time study or a lighter semester), or as many as five, six, or even more in others (though this is less common and usually requires careful planning and strong time management skills). You should always check your university's guidelines and consult with an academic advisor to determine the appropriate number of subjects for your situation.