Online screening tests in early January, then assessment centre for me was 1st Feb, then invited for final round interview which was 14th Feb.
Two interviews in assessment centre - unstructured, which was 25 minutes of competency based / motivational questions, and 20 minutes of a market sizing question which then led to a simple case study (e.g. how to increase profit); and structured, where I was given 15 minutes to analyse about 7 pages of information/data for a case study question, and then had a 1 to 1 discussion for around 40 minutes.
For the final round interview, there were three interviews - the first two are unstructured and structured, just like the assessment centre. The unstructured interview, however, for me, was 35 minutes of discussing my CV and my motivations for applying, then 10 minutes of market sizing. The structured interview was identical to the assessment centre - no difference in difficulty either in my opinion. The third interview was a presentation exercise, where I had to go through around 20 pages of information/data, draw visual aids, and come up with a recommendation to present for 10 minutes to two interviewers all within 30 minutes. The 10 minute presentation was followed by questions (and criticism) from the interviewers, and other broad questions regarding the topic.