Mark James Adams"The Unusual Value of Long-Term Studies of Individuals" Review of the Isle of Rum Red Deer Project, but many lessons in the value or long-term studies apply to humans, too.
https://www.annualreviews.org/doi/full/10.1146/annurev-ecolsys-012722-024041
More on the value of long-term studies https://www.nature.com/articles/s41559-022-01940-7
The expanding value of long-term studies of individuals in the wild - Nature Ecology & Evolution
Over the past seventy-five years, long-term population studies of individual organisms in their natural environments have been influential in illuminating how ecological and evolutionary processes operate, and the extent of variation and temporal change in these processes. As these studies have matured, the incorporation of new technologies has generated an ever-broadening perspective, from molecular and genomic to landscape-level analyses facilitated by remote-sensing.