Should I rely on coaching notes or make my own notes from standard books for UPSC?

The most effective strategy is a hybrid approach: use coaching notes to save time on the static syllabus, but create your own notes for the dynamic and analytical portions of the exam.
Coaching notes are pre-summarised versions of standard textbooks. They are excellent "shortcuts" for factual subjects because they filter out irrelevant details and align strictly with the syllabus. However, relying solely on them can be risky; if you skip the original source, you may miss the underlying logic needed to tackle complex, indirect questions in the Prelims.
Self-made notes are your greatest asset for the Mains. The act of writing forces you to process and synthesise information, which significantly improves long-term retention. Personalised notes also allow you to integrate current affairs—such as new Supreme Court judgments or economic data—directly into static topics. Crucially, during the high-pressure days of the Mains exam, you won't have time to re-read textbooks; you will need your own 1–2 page summaries for rapid revision.
To be efficient, don't make notes for everything. For books like Laxmikanth or Spectrum, which are already structured like notes, simply highlight the text. Instead, focus your note-making efforts on complex editorial issues, your Optional subject, and value-addition data. Using digital tools like OneNote or Evernote can make updating these notes much easier as new information emerges.