There can be a lot of reasons why you would choose to take the route of doing the bare minimum, and some are understandable. If you know that the course you want doesn’t require high points, then you might tend to relax a bit too much, in confidence that you don’t need to make any more effort than is necessary to get those points. Or maybe you have a job too that you need to allocate time to. But it is more often because of less noble reasons: like simple laziness, a (severely misguided) belief in the ingenuity of the approach, the fact that there’s important TV show or game on the telly, or because of an unwillingness to make some sacrifices such as reducing one’s social life for a short period of time. For many reasons this is an approach that will quite possibly be regretted.
At Leaving Certificate age, things can seem a certain way. I can recall time moving so slowly during double Maths that even the very concept of the future existing at all seemed remote, unknowable and unlikely.