However, evaluations can vary greatly depending on who the evaluator is. Experienced and expertly trained evaluators will employ many methods of information gathering so they are not relying too heavily on information from a single source. Many use face-to-face interviews, questionnaires, and psychological testing, in addition to reviewing documents and contacting professionals and others involved with the family. Because each situation is unique, the same evaluator may use different methodologies for different cases. For example, home visits are rarely helpful for most cases, but for some cases they may be necessary. Expertly trained evaluators will spend enough time with each parent over several meetings to sufficiently understand who they are, as well as comprehend the relevant issues. They know how to get to know the children and come to understand what they need without placing pressure on them to choose sides, being too intrusive, or involving them further in parental conflict.