We recently built a website that meets the minimum viable product for a customer in under 24 working hours. An Enterprise Accelerator is the key, the secret sauce. This particular accelerator is built upon SCORE, but these principles can be applied to any CMS accelerator platform.
SCORE's Bootstrap UI layer delivers core functionality for the most commonly used components in web development. When the core offering does not satisfy your requirements, though, one option may be to extend SCORE components with custom functionality.