I found when I was doing the group things that it always came down to the last few hours but I got myself familiar with other people's portions (it's good to know their portions for any "test"/final anyway) in case I had to cobble something together; it isn't "fair" when one or two people have to do more work but I found that, in the end, it made what I knew stronger and helped me with my final grade and that was my point in taking the course so I did whatever work made me comfortable that at least how I presented would "work".

The teacher is not blind and will know what's going on and who contributed most/least by the presentation itself and the ones I had to work with adjusted grades subtly at the end; if you're getting an "A" in the course and you all only get a "C" on this project because of others, you'll still get that "A"; the group thing is really used to "confirm" that you are doing the work and give a "true" reading of your work ethic, etc.