I think once you “Return” the tag, it stops the calculating of activity.
The presumption is that you “return” the tag in real time as it was counted, and that any transactions also occur in real time. Thus it is moving the target in sync with you.
But… if you are like us and do the counts and transactions not in real-time, then yeah you are stuck second-guessing the activity for the rest of your employment there.
The variance formula is
Count - (freeze + activity) = variance
So if you need to outsmart it (we do), this is the formula.
A recent discussion: