David Kimura PRO said over 5 years ago on Refactoring Models :
Hello Steve, it really is the code organization which benefits from extracting the methods out. I've worked on similar applications in terms of size as the GitLab app and the fat models made it very difficult to work on. Grouping and moving ideas, like the friendships in the episode example, make the overall maintenance of the model easier over time. Yes, things are now in multiple files, but it ended up still being preferred over a large model. Ultimately, it does come down to the team's preference and their style of coding in which case I think should always be consistent on a per project basis. However, bringing a new person on board, it would be overwhelming to have to work in a large model like GitLab's user model. I consider most things, with exceptions, which makes something easier to maintain, lowering technical debt.