Say you have a chain of three tables, A, B and C that connect in that order, so your diagram looks like this:
A -< B -< C
There must be a key column on C that allows you to create a shortcut join of A -< C
So, A is Region Dim, B is Store Dim and C is Sales Fact.
If I want to know sales by region, I would pull objects from A and C.
As I have not pulled any objects from B, BO will change the join path to use the shortcut join.
As soon as you use anything from B, either as a condition or a result, then you MUST go through B.
A shortcut join is not needed, it is a tool that can be used if you can use it.