We use Jira to track development tasks, and have two states for review: Awaiting Review and Under Review. Every branch (and thus every PR) has a corresponding dev task. We configure Jira so it lights up the Review column in red when there are too many items in it. It's a fairly unsubtle hint that items in the column need to get reviewed before moving on to the next dev task.
We also use Stash (now Bitbucket) rather than Github, so we can configure it to trigger Jira state transitions.
Depending on how features get factored, you can end up requiring certain tasks as pre-requisites before other tasks can get started. Then there may be direct communication / nagging involved. But we try and cut things up a little bit differently, so that there's less scope for lag to impact overall feature delivery time. The main idea is to prevent PR reviews from being blockers for multiple people.
We also use Stash (now Bitbucket) rather than Github, so we can configure it to trigger Jira state transitions.
Depending on how features get factored, you can end up requiring certain tasks as pre-requisites before other tasks can get started. Then there may be direct communication / nagging involved. But we try and cut things up a little bit differently, so that there's less scope for lag to impact overall feature delivery time. The main idea is to prevent PR reviews from being blockers for multiple people.