I can't speak to server side development, but for ui applications, storing your models in a singleton can save you a lot of time. When you're developing apps it

I can't speak to server side development, but for ui applications, storing your models in a singleton can save you a lot of time. When you're developing apps its very easy to get stuck in a mindset that you only need certain data for each screen, but the truth is the data for one area will inevitably bleed over into other areas, and having a good way of updating and reflecting data to the areas needed is the sign of good architecture.