I am definitely guilt for that, but I find this approach really productive. We use small bug fixes as an opportunity to improve the code quality. Bigger PRs often introduce new features and take a lot of time, you know the other person is tired and needs to move on, so we focus on the bigger picture, requesting changes only if there is a bug or an important structural issue.

This is why I always rename all the variables in the project on each PR.

Ask him to do 500 lines and he will never look at it, making you wait forever

Just give them 10 lines at a time from the 500 lines one. Is this how micromanagement was born?