LMX2594: What is the VCO calibration data validity period?

I understand that using "full assist" VCO calibration mode, the preliminary steps are to:

1. Program the device to the desired frequency without assistance
2. Readback the calibration data (VCO_SEL, VCO_CAPCTRL, VCO_DACISET)
3. Store the calibration data for subsequent use in active duty

My question is: how often should the above process be re-run, i.e. how long is the stored calibration data valid for? For example, is it a one-off process, or should it be re-run every power cycle, once a week, once a year...?

Thanks.