Contact tracing is, as far as I've read, the very first strategy initiated by most Western governments and health organisations. In the early stages of reported cases.

As it stands, my country is still in relatively early stages compared to many others, and contact tracing became unviable as a first defence well over a week ago. Over 60% of our cases are community transmission.

We're still doing contact tracing, it's probably worthwhile, but it's not going to be a major factor in mitigation.