It depends on the school. Some schools have exam blocks, basically every few weeks or month you have a week of exams. At other schools, like mine, you have an exam every week. There is a ****load of material to cover, but if you keep up with the material and study every day, it's doable. I am typically in class 8-5 and then I come home and study for 2-3 hours, just looking over notes from the day. Weekends are the days I really cram and usually spend 8 or so hours in the library on both saturday and sunday.
None of the finals at my school are cumulative, in the sense that you won't see stuff on the last exam that were covered on the first exam. However, some concepts build upon each other so you do need a good foundation.