Hi!

Two points:

1. Answering your question: yes, this is mutually exclusive!

2. BUT at the same time it is a very weak structure to address the client problem that was stated ("Why are sales low / declining?"). These buckets you otlined are arbitrary and not derived from any logic or rigorous thinking process! It is EXACTLY why 95% of people who try to perfectionize the stuff they read in casebooks fail in their interviews - because it actually prevents the interviewer to see your capacity to solve problems in a REPEATABLE way (i.e., by logic!). 

A much much better way to address the question would be to first disaggregate the focus metric (sales) according to its definition (if necessary, verify the definition in the specific business context of the client!). 

Then you check for every sub-branch, which value has negatively changed, and then drill down deeper on that path. (Those drivers that did not negatively change are excluded from the further analysis) 

Then, once you have drilled and narrowed down two or three levels deep, you have isolated the numerical problem driver → so now you have found WHAT has caused the issue. 

The next step is then to run a qualitative analysis of this specific problem driver, to find out the underlying REASONS for WHY the driver has declined. HERE is where such buckets that you outlined can be used in a much more intelligent way!

This is just a rough outline of a rigorous approach, but I hope you can already see that it is superior to any set “buckets and bullet points” you could ever come up with, because it shows the qualities that the interviewer is expected to find in you: the ability to take any problem, operationalize it, drill to its core, and address it at the core.

Unfortunately the typical case resources are brainwashing candidates into this weak framework thinking, leading to months of preparation where candidates are just becoming perfect in doing the wrong things.

Cheers, Sidi