We had 10 'modules' in first year. In semester 1, there were 2 which had final exams in December (so 10 weeks' teaching then wk 11 was the exam), 1 which had the final exam in January (in the middle of week 2 of the next semester - no separate exam season), and the other 2 exams in May (in the actual exam season). The semester 2 modules, 1 had a wk11 exam before the easter break, the other 4 had exam season exams in May.
A similar thing in second year, but in third year every module's final was in the May exam season.
The ones which fell in semester time were counted as 'class tests' rather than exams (as they're not regulated by the central exam office). I believe that there was a rule about what proportion of your assessments could be done in-department, and what had to be done in central exams.
I do think it is good to have some mid-year assessments (including essays etc) but the end of year exams does help you to have more time to reflect and make connections with what you are actually learning. Wherever you have a test immediately after the last week of teaching, it tended to be more MCQs and more surface-level knowledge. You need synthesis time.
Where I work now, they have two separate exam seasons (whole of January and whole of May) and I think it really disrupts the flow of teaching (especially for those 'long thin' modules).