If you have an architecture document, readmes for related services, relevant code from related services and such assembled for a LLM, it can do a pretty solid review even on microservices. It can catch parameter mismatches/edge cases, instrument logging end to end, do some reasonable flow modeling, etc. It can also point out when uncovered code is a risk, and do a sanity check on tests.

In order to be time efficient, human review should focus on the 'what' rather than the 'how' in most cases.