I was recently working with a client who wanted a reasonably large subsystem added to Optimizely that would add automated management to their content. While cutting the code for this, I found myself writing similar code across multiple classes. The reason why I had to write it that way was: 1) The client was currently on CMS11 and didn't have access to newer language features; 2) The hierarchy of the classes prevented me from inserting a common ancestor. Thankfully, .NET has expanded the functionality of interfaces, so we can take advantage of those within Optimizely. With .NET 5, Microsoft introduced default implementations on interfaces. Now interfaces can bring along a default implementation. Resulting in all classes that implement the interface can use the default implementation or override it with custom logic. Enough text! Let's code! Original Interface The following code is something that we'd create for an Optimizely experiment: using OptimizelySDK; using Optimizely