The authors make much of the idea of deliberate practice, championed by Ericsson.25 It seems to me that, although there appears little question that practice leads to improvement, too little thought is given to what kind of practice. Deliberate practice for the pianist is not the same as for the chess master. Pianists must repeat the same passage again and again; repeated movements is all. Chess masters are unlikely to repeat the same move again and again; instead, they must practice the many variations in the midgame and reason their way through multiple strategies. Further, chess masters do not need a board to do it on; they play chess as well without a chess board as with. When a beginner is learning suturing, I suspect that like piano-playing, many, many trials on something low fidelity, such as a pig's foot, would be the quickest way to mastery. On the other hand, auscultation is primarily a matter of learning to recognize the many ways mitral stenosis can sound and how it differs from mitral regurgitation. Like chess, this issue is of multiple variation, and I expect that repeatedly practicing putting the stethoscope on the chest, when it's always the same heart sounds, will likely lead to little improvement. Recognition of heart sounds can likely be accomplished nearly as well with a CD-ROM as with a high-fidelity simulator.26 As far as experts tuning up their reasoning skills, I expect that deliberate practice is actually provided most effectively when accompanied by coffee in the physician's lounge, and like for the chess master, no physical environment, simulated or otherwise, is necessary. In short, although simulation will have an increased role in CME for all the reasons outlined by the authors, its role may be circumscribed, and it is not necessarily the case that high fidelity (and high cost) is a prerequisite.