The sources provided do not offer any information on how often Lipitor users should swim. Lipitor is a medication used to lower cholesterol levels in the blood, and it is typically taken once a day as prescribed by a healthcare provider [1]. The American Heart Association suggests that physical activity, including swimming, can be beneficial for individuals with high cholesterol levels [2]. However, the frequency of swimming or any other physical activity should be determined based on individual health conditions and recommendations from a healthcare provider. Swimming can be a low-impact exercise that is easy on the joints and can help improve cardiovascular health, but it is important to consult with a healthcare provider before starting any new exercise regimen [3].

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/LIPITOR
[2] https://www.ahajournals.org/doi/full/10.1161/CIRCRESAHA.118.312782
[3] https://www.nhs.uk/conditions/transient-ischaemic-attack-tia/treatment/