My preferred way of doing PRs/Code Review echoes some of the statements below, but also requires the engineer to do the following:

1) Each PR (even if it's part of a larger whole) can be committed and released independently. 2) Each PR has a description of what it's doing, why it's doing what it's doing, and if it's part of a larger whole, how it fits into the broader narrative. 3) PRs are focused - meaning that QOL or minor bugfixes should not be part of a change that is tackling something else. 4) PRs are as small as possible to cover the issue at hand. 5) All PRs are tested and testing evidence is presented. 6) When a PR is committed to master, the final narrative in step 1) is the Git commit, along with the testing evidence, includes the JIRA ticket number in the headline, and the reviewer in the body of the git commit.

This way we have a clean, auditable, searchable history with meaningful commit history that can help reconstruct the narrative of a change and be used as a guide when looking at a change in, say, a year.