That's just bad outdated practice. It leads to cramming and less remembering than of the demand is for students to do work and show learning and effort throughout the year.
Which to me seems the best way, you still have to learn throughout the year. Especially to avoid cheating this works nice. And as an aside, most people I know that did a year abroad in the US got 1-2 grades higher, as it was quite easy to just farm extra credits.