4 years, 160 credits, 40 credits each year. Every year of university should be equally important, right? Wrong. Because of the aggregation of grades, each year gets gradually less important, at least psychologically. In first year, everyone starts on a clean slate. At the end of first year, the grades you receive are all you have. Each subsequent year's results are coloured by the results of preceding years.
This means that earlier results have a more significant impact on one's final class of honours and class rank than the later years, with first year being the most important. This is a counter-intuitive claim that is mathematically false but very true psychologically. I imagine it is a psychological pseudo-Monty Hall or Bertrand's box.
Consider two students. Amycus scores straight As in his first two years and straight Cs in his last two years to graduate with a B average in the middle of his class in the upper division of the second class of honours. His sister Alecto scores straight Cs in her first two years and straight As in her last two to graduate with the exact same rank as her brother.
Which would you prefer? I would surely prefer to undergo Amycus' university experience than Alecto's. At the end of their second year, Alecto had no chance at all of graduating with an A average. It would take a great deal of courage and discipline to score well when the rewards for doing so do not beckon. Amycus, on the other hand, had every chance of graduating at the top of his class when reckoning his prospects after his second year. That he did not is unfortunate, but the glowing promise of the future is far more preferable than the view from a grimy academic pit. In any case, he cruised to a decent result probably without much effort.
This can perhaps be summed up thus: to do well in first year, one needs to do just that: do well. But to do well in the later years, one may need to do extremely well if he had not done so earlier, or he may be able to relax if he had done well earlier. The overall impact of doing well or doing badly shrinks.
