The Department of Homeland Security Office of Inspector General (OIG) report on the L-1 visa program finds that Service guidance regarding specialized knowledge is not applied consistently and that more training at both CBP and USCIS is needed. For instance, the Report states this about the L-1B program:

In our 2006 report Review of Vulnerabilities and Potential Abuses of the L-1Visa Program (OIG-06-22, January 2006), we wrote: “One Southeast Asian visa section reported officers do not have the knowledge or the guidance necessary
to determine whether such work involves specialized knowledge, except in the most clear cut cases.” During this review, we determined that despite efforts to implement guidance that has been provided, confusion about the application of specialized knowledge still results in inconsistent adjudications.

The Report recommends:

Publish new guidance to clarify the USCIS interpretation of specialized knowledge. This guidance should be sufficiently explicit to give adjudicators an improved basis for determining whether employees of a petitioning entity possess specialized knowledge.