A caveat - "specific" is not the same as "detailed". An exercise which teaches the latter may fail to hit the former.

"Detailed" is a listing of all your customers with a testimonial from each of them, many of which will be redundant, others irrelevant ("pretty home page design"). "Specific" picks out the particular thing that serves your customer better than the competition.

Being able to recognize that a given example is particularly illustrative - an examplar - is a subskill.