This can be inefficient depending from the language and the compiler. The compiler many not always know that the this that you return is the same of the object

This can be inefficient depending from the language and the compiler. The compiler many not always know that the this that you return is the same of the object you are calling the method to, and that can prevent further optimizations. I don't see either any readability advantages of doing so, doing that just for not typing the name of the variable is nonsense, also the code is less clear to the reader (you have to know that the method that you call returns the same objects, it's not obvious, it can as well return another object, or a copy of that object). It's more explicit doing it the normal way.