Large modifications means that they are working on a feature for a relatively long time and very frequently need to do modifications to large swaths of the code base. Oh, and the common theme for all of them is that they are all big enough that it means that you cannot just merge back into the main branch. There are often a lot of failing tests or even uncompilable state during a long refactoring session.
The good thing is that we are pretty good about making sure that we merge from the main branch on a regular basis. The bad thing is that once we start merging those big changes, the other large refactoring are going to have to deal with a lot of changes happening very quickly.
Hence, the merge games. The fastest one of those team is able to hit the “can we put this in the main branch” point, the less work it is going to be for them. On the other hand, the slower you are in getting to that point, the more conflicts you are likely to run into and have to resolve.
I don’t think it would be a best seller book series and I doubt that I’ll get a movie deal from it, but in a certain select group of people, I think that this will be an amazingly fun game (as long as you aren’t the one left holding the shitty end of the merge conflicts).