So as of right now, Ross does not have two curriculum tracks anymore. They took out the X (accelerated) track about a year ish ago (give or take), so they only have the standard "C" track which is 5 semesters. I did the C curriculum but had friends in X track, but since Ross is only C track now, maybe I can give a different perspective. I think there are a few big "checkpoints" throughout your preclinical/basic science years. These checkpoints/areas are the place where students end up struggle/fail out the most.
The first point is Semester 1 which is probably not too surprising. Ross and other caribbean med schools accept weaker students compared to the US students, and they also accept a larger amount of students. For those reasons, there will be a higher probability of students not passing. There are many reasons why students fail/drop out from Sem 1. First, they were never ready both academically and mentally. Academically, they might not have what it take and don't end up putting in the hours to make up their shortcomings, or if they realize too late. Some students end up never adapting to the fast pace and rigor of the medical school curriculum. Some were not meant to be accepted to medical school and they need time to work and develop the proper habits to suvvcceed. Mentally involves moving from a first world country to a third world country. The transition is not easy and it requires you to be flexible, adaptable and being able to overcome what gets thrown at you. Studying medicine is not easy already, but adding the fact you are doing in a third world country increases the difficulty. Another reason would be students not studying enough, which is kinda similar to what i said above. The island life is actually really fun because it's a tourist island. There are a lot of parties, activities, etc to do near the beaches. The beaches are so much better than what we have here in the US. It's incredibly fun, but also if you're not studying most of the time there, then you have a high chance of failing the semester. I've seen students party and not passing.
The second point would be Semester 3. This is because of how the semester is structured. Exams at Ross are often called "mini". I don't know why it's called that, but I do know it's been called that for a very long time and it stuck since. In this semester, Mini 1 is very close to the Final in term of weight for your grade breakdown. Mini 1 was like 29% and the Final was like 30%. Mini 1 is difficult because you're being introduced to Microbio and microbio pharm. There are A LOT of organisms (bacteria, viruses, etc) and you have to know everything about htem as well. So it's easy to say that if you don't do well on Mini 1, you will be in danger of not passing. The other Minis are still worth a decent amount too, like 16% and 20% IIRC.
If a student can get through semester 3, then they should be able to finish semester 5 (for the most part). However, there is another "point" that poses difficulty for students after preclinical/basic sciences. It's COMP/CBSE for Step 1. You only get 3 chances to pass COMP and if you can't, you're subjected to dismissal or you would have to voluntarily withdraw from the program. On paper, they say 3 chances, but in reality, you might be able to get a 4th or 5th depending on your situation (ymmv). From my personal experience, a good amount of Ross students don't prep for Step 1 til after Semester 5. Compared this to US medical students who prep around the start of their second year so by the time they finish their preclinical and enter their dedicated, it's more streamlined and they're just wrapping up their studies within 4-6 weeks. This is what makes it so difficult and some students get stuck here for a bit of time. Some might not even make it out. That's the third point.
IMO if you can get past the third point, you have a very high likelihood of finishing third year, COMP/CBSE for Step 2, Step 2, and eventually graduating. The rest is pretty much downhill from here on out as long as you keep up with your studies. Most students who make it this far are more than capable of finishing 3rd/4th year and graduating. Of course, this isn't to say it's easy from that point on. You just get better overall as a student by this point.
Ross and other caribbean schools are difficult. Everyday you're constantly worrying about what is the next "thing" that'll get you in trouble/failing out. Those are the major checkpoints but there are A LOT of smaller checkpoints, and too many to list. Most exist during your first two years, and also shelf exams during your third year. If you're thinking of attending a caribbean medical school, whether that'd be ross or sgu, I would advise you to go to a US medical school first. I've lost a lot of my classmates along the way and it's difficult to keep tabs who is still in or out now. The attrition rate is high and it's no joke.