Your choice. If the spot you are working on is focused, you don't need to move it.
If the area you are working on is much larger, then moving it over time would be appropriate. However, you don't need to move it as if you are massaging the area.
Depending on how many frequencies you are using (I just use 1 typically), you may wish to move it every 15m or after one loop of your frequency list has been applied.
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