Ok, I was pretty sure having to recalibrate every time it was used was incorrect. Just need to recalibrate when not wanting to measure at the same point as your previous calibration.
My understanding from the users guides I have read is that any time you change frequencies, you set the new range and run the cal.
IMHO unless you use the device constantly at a bench always using the same frequency, it is good practice to check the cal every time you use. I am not always 100% positive which frequency it was set for since I do not use it daily.