The frequency of checking Lipitor dosage should be determined by your healthcare provider based on your individual medical condition and response to the medication. Regular monitoring of your Lipitor dosage may be necessary to ensure its effectiveness and to adjust the dosage if needed. It is important to follow your healthcare provider's instructions and attend scheduled appointments to discuss your Lipitor dosage and any potential side effects.

Sources:
[1] drugpatentwatch.com
[2] nhs.uk
[3] drugs.com