Well, after many testing, i think Ulrich's rule is incorrect. This is a programming bug, not a feature. It stops working even when unlimit fuel + unlimit weapon is enabled.
You have around 32 range-finding times. After that, it begins to stop working. Sometimes at 32th, sometimes at 38th, YMMV.
If you've measured < 32 times, just relax, firing ATGM at any time. It doesn't need any 30 minutes rest between 16 measure cycles. Just land, reload missile, and shoot.
If you>32 times, You're no longer able to deploy ATGM, no matter how long you sleep at helipad; unless you crash/respawn.
However, you're still able to measure range for gun. Just flip the laser standby switch, press lock, then you have correct range for the gun.
Therefore, use it wisely, make every shot count. Only turn on laser for important targets: SAM, AAA, advancing/defending tank column. Pick harmless remain targets by gun.