There are many styles of neuropsychological practice, but the primary purpose of all assessments is to provide an understanding of cognition and how it relates to known or suspected brain conditions. The tools that the clinician selects to explore these hypotheses are important. Whilst some clinicians prefer tools with extensive psychometric data, others are more comfortable with combining clinical judgement with observations on a smaller number of tasks. The relative merits of these approaches are examined using hypothetical test data.