Jul 14, 2014 08:39 AM|jammycakes|LINK
Don't use a separate project in your solution for each layer. It just adds friction and complexity (slows down compilation, makes upgrading NuGet packages harder, adds unnecessary complexity around circular dependencies) without giving you any benefit whatsoever.
Follow the Common Closure Principle instead: classes that change together should be packaged together. If you want to organise your code by layers, that's what namespaces are for.
For a basic web application, your solution needs just three projects: