To evaluate the relevance of their chosen optional subjects for UPSC, aspirants should assess factors such as personal interest, past academic performance, and the availability of study resources. It's important to review syllabus coverage and whether the subject complements general studies. Analyzing previous years' question trends can provide insight into the subject's scoring potential. Additionally, consulting mentors or successful candidates can offer valuable perspectives. Ultimately, the chosen optional should resonate with the candidate's strengths to maximize performance in the Mains exam.