Objective: There has been increasing interest in recent years in the variation in assessment practices within the neuropsychology profession. This article explores one of the central areas of variation by reviewing the issues surrounding brief versus more comprehensive assessments and some of the advantages and disadvantages of the two approaches. Methods: Some of the many factors influencing the length of assessments that neuropsychologists choose to conduct, and the way these are interpreted, are discussed. These factors include the principles of test selection, the potential of measurement error, the emphasis we place on our previous experience to guide selection and interpretation of tests, and our ethical and legal obligations. The potential utility of employing testing assistants to perform the routine parts of assessments is also explored. Results: While there can be some disadvantages to conducting comprehensive assessments, many benefits of this approach are also identified. Conclusions: Overall, it is argued that neuropsychologists should abide by evidence-based practices that stem from scientific theory as opposed to conducting less reliable assessments that may be largely driven by cost-effectiveness.