The style of research further exacerbates this problem because the required time is frequently unknown. A further problem is that the student does not have to complete the research to graduate, yet must complete the course work. Thus course work must take precedence. After having experiences with such students, some of the research professors have become leery of taking undergraduate students. For some professors the background of an undergraduate is insufficient to conduct the required research.
Few professors can resist a strong case from a good student.