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.

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?

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