Usually u are dedicated to a single project for one entire semester. In the earlier years they give you little exercises and research projects which pertain (or should pertain) to your semesters work. The mid semester review is a staple when it comes to American Architectural schools. Sometimes (depending on the professor) You can have reviews every week, every month or even just the mid and final review (I once had 2 reviews a every week). Now each review has different levels of intensity (casual-formal). It can be just amongst ur peers and professor, the professor may ask a friend to come in. Now desk crits and 1 on 1 pinups are another thing on its own but is still essential to studio. The mid and final review usually calls in the big guns. I’m talking the dean/chair or ur school, the coordinators of Master or Undergrad programs and most importantly guest Reviewers. These people are usually flown in across the country (in sum cases the world). Depending on ur school and professors the guest reviewers will vary. My school had a lot of Princeton grads for professors so they pulled in sum big names from other schools and employees from big firms. This once happened in another school where Peter Eisenman, Thom Mayne, Wolf Prix and Raimund Abraham were in the same crit arguing. More minds mean more conflict. It can be good or bad.