You don't have to worry about the class precedence list for methods and slots inherited from only one superclass or another. The advantage of using auxiliary methods is that it makes it quite clear which methods are primarily responsible for implementing the generic function and which ones are only contributing additional bits of functionality. Of course, if you're going to rely on a coding convention--that every method calls CALL-NEXT-METHOD--to ensure all the applicable methods run at some point, you should think about using auxiliary methods instead. Thus, if you want to be able to reuse the code that prints the savings-account part of the statement, you'll need to break that code into a separate function, which you can then call directly from both the money-market-account and savings-account print-statement methods. The more proxy components are located between client and server, the more is the latency’s part in the response time. So Common Lisp uses a second rule that sorts unrelated superclasses according to the order they're listed in the DEFCLASS's direct superclass list--classes earlier in the list are considered more specific than classes later in the list. The problem is that while you can use CALL-NEXT-METHOD to call "up" to the next most specific method, namely, the one specialized on checking-account, there's no way to invoke a particular less-specific method, such as the one specialized on savings-account.