In our experience, it depends on the task and the language. In the case of trivial or boilerplate code, even if someone pushes 3k-4k lines of code in one day, it's manageable because you can just go through it. However, 3k lines of interconnected modules, complex interactions, and intricate logic require a lot of brainpower and time to review properly and in most cases, there are multiple bugs, edge cases that haven't been considered, and other issues scattered throughout the code.