>Composition makes code inherently more maintainable and easier to refactor.

My understanding of composition comes from interfaces in C#. In my experience composition is actually more difficult to code and refactor, because it leads to bloat from repeated code as you cannot simply inherit. Refactoring then can become tedious as you may need to manually edit every repeated code block. Whereas with inheritance I define a function once and override it where necessary.

Am I misunderstanding something?