Categories or Structures: Most efficient way to organize FAQ sections Working on a plan for a site that has multiple audiences, with a FAQ section for each audience.  


FAQ entries are organized by Topic (Finance, Advertising, Publicity)


each FAQ entry can be associated with multiple topics  

FAQS and Topics are also organized by audience: (trainee, associate, lead)


a given FAQ entry or an entire Topic full of entries can be associated with multiple Audiences



It would be nice to be able to order the entries in each topic, but not a must have. 

The three separate FAQ pages would have content that maps out like this, as an example:

Trainee Audience page

Advertising
     Ad Entry 1
     Ad Entry 2
Finance
     Fin Entry 1
Publicity
     Pub Entry 1


Associate Audience page

Advertising
     Ad Entry 2
     Ad Entry 3
Publicity
     Pub Entry 2


Lead Audience page

Advertising
     Ad Entry 1
     Ad Entry 2
     Ad Entry 3
Finance
     Fin Entry 1
     Fin Entry 2
     Fin Entry 3


I know that this can be accomplished in various ways using categories, structures, and related entries, but I'm aiming for efficiency, then ease of editing for the users.

I've tentatively landed on this: 
One main Structure, with Topic and FAQ entry types. Both entry types have a Category field to select audience

but not sure if I'm missing a better option for performance/ease of use.  Any advice is appreciated!
If your clients wants to have control about the order of the entries for each audience,  e.g. 

 Trainee
 Advertising
    Ad Entry 2
    Ad Entry 3

 Associate
 Advertising
    Ad Entry 3
    Ad Entry 1
    Ad Entry 2


a good solution might be a entries field. The ability to simply drag and drop entries to change the order is the most intuitive option from my experience. If you have many entries you could combine both logics - e.g. render first all elements that you selected with the entries field and after that add the missing ones according to your categories / structure.