Many clients ask their experts to look at evidence through the lens of specifically how they think it will be useful to them. A good expert will listen carefully. Experienced lawyers and experts also know that often there are often other aspects of a forensic examination which may become important, although outside the scope of a stated need.
In this regard the input a client will ultimately need can be overwhelming and even seem irrelevant if delivered without exposure to the experts conception of the case. Thus there really needs to be a period during which both parties inform each other. The relationship then deepens and both client and expert become more able to process additional input. If this sounds like an art form it really is. Ultimately the outcome of a case depends on how well everyone does his job with respect to informing the others on the team.