In reviewing current fertility tracking methods, I am interested in exploring the clinical accuracy and applicability of conception calendars, particularly in populations with variable menstrual cycle lengths. How does the timing predicted by standard conception calendars align with ovulatory markers such as luteinizing hormone surges or basal body temperature shifts in such cases? Furthermore, what modifications or adjunctive techniques (e.g., hormonal assays or ultrasound evaluation) are recommended to enhance the precision of these calendars when advising patients on optimal conception timing? Discussions on recent empirical studies or meta-analyses addressing these aspects would be highly valuable.