Think about it this way. If you work with a large team which is split between multiple locations and each developer has a set of tasks to work on, having everyt

Think about it this way. If you work with a large team which is split between multiple locations and each developer has a set of tasks to work on, having everything in 1 source file means everyone has to update the same file regardless of what they are actually working on. Using your example, if you have all_models.rb, any change needed for any model would mean committing the entire source code in the file. Huge risk. The idea of multiple files is to have a modular approach which means easy to divide tasks, collaborate and mange version controls. Sure it means having to traverse through multiple directories/paths/files but this small sacrifice is nothing compared to the risk of having large source files.