If your research supervisor, PI, or labmate asks, “How late can you stay at the lab today?” don’t answer with: “Whenever—it doesn’t matter.” Because it does matter.
If you give an open-ended answer, you might find yourself finishing at 4 AM, exhausted and hangry (especially if you already ate your snacks and the vending machine takes your money without giving you food).
Remember, research might not be a 9 to 5 activity for the labmate who’s asking. Always give a time window even if it isn’t precise such as “4:30 to 5:30,” or your absolute cut-off time “7 PM.”