Nope it doesnt end even after you are activated once. You are still liable for call ups during your mob manning period. This is in case of any real ops during your mob manning
Official answer is no
Actually top commanders like S1 & CO in your unit and higher HQ will know how many activation during ops manning period cause they needs to arrange with Mindef for notification by open or silent mode.
So it will be good to check with them for advise cause by default, you should standby for ops manning period.