Is it possible? Can a person cram the night before the GED Tests and successfully pass all five of them? I doubt it.
First of all, you will not want to take all five of the GED tests at once... unless you are required to do so. Wisconsin lets GED Candidates take one test at a time, and that is what I recommend. Check out it before you sign up for the test/s.
So.. can a person successfully cram and take one test? Depends on what that test is and how much background the person has in it. If a person has fairly good reading skills, they may be able to pass the GED Reading Test, GED Social Studies Test, and the GED Science Test. But I would highly recommend that the person take a "practice GED test" in each area prior to taking the "official"GED test. The practice test will be a pretty good indicator as to how a person will do on the "official" GED test.
What about the math or writing test? Again, I would recommend a practice GED test. The GED Math and GED Writing test are the two tests that most students will need some help with.
So... I would NOT recommend cramming for any of the GED tests. I do realize that a student will be anxious to finish ASAP, but as a teacher try to get them to slow down... at least a little bit so that they will have a greater chance of success. As a GED student, be patient with yourself and take your time so that you are successful when you do take the test/s.