Recent quotes:

N-of-1 Clinical Trials: Removing the Hay to Find the Needle | Clinical Chemistry

an observed lack of universality in response to interventions and a greater focus on the individual with the emergence of precision medicine. A strong focus on the uniqueness of each individual has led to many discoveries in cancer diagnostics and drug efficacy and has prompted the US Food and Drug Administration to relabel numerous approved drugs to include pharmacogenomics information.

Evaluation of person-level heterogeneity of treatment effects in published multiperson N-of-1 studies: systematic review and reanalysis | BMJ Open

person-level HTE is common and often substantial