dev process -- copying/using logic from other apps

Hi. Looking to get feedback from list if you don't mind. If one is looking to create/build a webapp, I'm thinking it makes sense to look over open source apps (good ones, not the garbage ones!) that are created using your stack. Example, I've defined laravel/mysql/etc.. My potential app will have some of the funcs: User/Profile Management Email Send/Manage/Process func Admin Portal/Process -- diff functions userAdmin systemAdmin etc.. THe idea being, if I've defined my tch (laravel), and I roughly know my pieces of the webapp, doesn't it make sense to find/copy/'use some pieces of other apps as guides to build the init mockup/model to be able to then drive the overall process? In other words, why recreate from scratch, that which is more or less already created a bunch of times..(This would also include some of the ux/ui look/feel frontside stuff. thoughts? ps, in the event you agree with the above, i might repost asking the list if you have any apps that have certain functions/features that I'm looking for! thanks!!