A "cram session" refers to a short period of intense studying or preparation for an exam or test. It's when someone tries to quickly learn a lot of information in a limited amount of time. Full definition
Transfer student Adrian Bazbaz wasn't used to the late night cramming sessions and sleep deprived lifestyles of his fellow classmates at the school, so he decided to do something about it. (relevantmagazine.com)
Readings are assigned as preparatory work so a student will show up to class somewhat familiar with a topic and able to engage in discourse on the topic by forming an informed opinion; unfortunately this is not occurring; readings, if they get done at all, are being done in cram sessions after the fact or in annotated notes endeavours at the end of term and this is not the purpose of assigned readings. (slaw.ca)
The challenge is to avoid the allure of cramming sessions and instead ensure that rigorous instruction is happening daily throughout the school year — a few days of cramming is not an effective substitute for deep learning. (assessmenteducation.org)