In the aftermath of the Covid-19 pandemic, Box’s wisdom regarding models seems as prescient as ever. Much of the more dubious modelling performed during this period has generated substantial criticism.(1) Modelling complex systems involving human beings, incapable of reliably living up to the role of rational actor is particularly fraught with danger.(2) Given the influence of much of this modelling over public health decision-making, it is tempting to add “some are harmful,” to Box’s aphorism. It is therefore, with perhaps some trepidation that we approach the report by Donnelly et al., published in this edition of the Annals of the American Thoracic Society(3). The question follows, is their model useful or potentially harmful?