As several commentators on the consulting sector have pointed out, both the outcome and success of knowledge-intensive services  are very difficult to measure" (Armbruster, 2004, p. 1248).
Another presumption made by Armbruster is the state of uncertainty and doubtful quality of service provided by management consulting firms. In fact, there is no legislation or codes of practice which protect both service providers and users in sense of artificial information vacuums created by influential groups. In addition, credence goods market dictates its own rules: when selecting personnel, organization are aimed at finding persons who will easily fit into business environment and identify themselves with this area, or figuratively speaking, dissolve and serve merely as representatives of certain business segment.
Human Resource Management perfectly functions when described in the range of related theories, models and concepts, but they are often barely applicable because of the leading trends in contemporary business. First of all, so-called 'war for talents' (ibid, p.1249) shows the need for young and creative university graduates, who have degree, but lack job experience. Nevertheless, such immature specialists often work as advisors and speak to their experienced colleagues in the manner of superiority. Consulting firms prominently demonstrate this trend, as personnel selection process in this area doesn't include tests, associated with correspondence to organizational philosophy and psychology, but merely on the simple tool known as case-study interview - specific problem assigned to a candidate. On the other hand, the scholar indicates that there is a stable set of criteria, which should be included into the interview: discussion of market size and appropriate case study ( number of small businesses within certain area, calculation of computerization trends), business cases (such assignment include strategic planning for certain company, SWOT-analysis and other important business plan preparation tools) and brainteasers (very specific cases within narrow or poorly-researched area, which are to be resolved by an interviewee by using 'realistic approach'). In spite of obvious diversity and segmentation existing in our business area, interviews are typical: " The candidate is expected to make assumptions in order to have a basis for quantitative calculations" (ibid, p. 1254)
That is to say, rationality in management consulting was researched by many more specialists and the results show almost no distinctions. Gradual prevalence of case-study interview was shown in Peter Block's survey (2004), in which he draws an interrelation between the growth of small businesses and the need for introducing case studies as the framework for successful interview. Cross et al (2001) hold that accessibility of information is one of the main factors in shaping knowledge, but consultants should try to make more specific and more goal-oriented queries, as they often underestimate of ignore such factors as peculiarities of collaboration between businesses (which businesses are more likely to cooperate), peculiarities of certain product (for instance, the fashion for some sports is falling, so the periods between purchasing new inventory sets is increasing) (Cross, 2001).