About the meaning of common here states that:
found frequently in many places or among many people
However, I feel that common is not only limited to the cases when something is frequent, but also it can be used when something is just not unusual, i.e., not as usual as frequent but is just as usual as some. For example, consider this sentence:
It is a common assumption in different areas of research.
I feel that this sentence is not wrong and means using the assumption is not strange and unusual in "different areas of research" (e.g., there are some areas, in which there are 2-3 papers that use it), and not that it is being used frequently, e.g., in 80% of the papers. Am I right? If not, what else can be used in the sentence instead of common for that purpose?