Do your part fully, then let the rest be someone else’s part. The group project will survive.

Anxiety about a shared outcome pushes you to extend your responsibility across the whole of it. That extension is exhausting and it also crowds other people out, since a job already being covered gives nobody a reason to step in. Finishing what is yours and then stopping is a complete performance, not a partial one.

Define your section clearly, do it to a standard you are content with, and then stop. Resist rewriting other people’s contributions the night before. The result may be less polished than you would like, and it will still be finished.