True story. I started studying for a final basically the night before the final, but quickly realized I just wanted to play video games instead.
So I spent an hour and a half pulling up all my previous scores in the class, including two copies of the syllabus from two places just to be sure. I made a spreadsheet (in OpenOffice at the time, haha) laying out the scores and weighting them a few different ways per interpretation of the syllabi.
All models basically indicated I could skip the final and sleep in and, worst case, still pass the class by something like 1.2%. I checked, double checked, triple checked my figures.
...and then I spent the night playing video games and purposely didn't set an alarm the next day.
I was very relieved to have passed the class by the 1.2%.
I was not a good student. I do not advise this. I think I graduated by like 0.1 above the minimum required GPA.