This excellent answer to a question about collision avoidance practices for launches begins with:

While the length of a launch window varies, launches within the window typically occur at discrete times - typically "launch on minute" or "launch on second". Often a common earth-relative trajectory is used for the entire window (or subsections thereof), and rotated to the correct inertial trajectory for each expected discrete launch time.

Launch on minute makes sense. Say you have a 30 minute window, there may be some planning advantages to having 31 well defined launch programs and collision-in-LEO avoidance checks (one at each minute mark) rather than 1801 of them, and even 1801 discrete programs might be safer than winging it on the millisecond. But I can also imagine hesitance to waste up to 59 seconds of additional hold if a hold could be released but it would put the launch at xx:01.

Question: Is "launch-on-minute"or or other discrete launch time protocols currently the norm for wide launch windows on orbital or deep space missions (not counting sounding rockets or other suborbital launches)

If there are some good counterexamples to the launch-on-minute practice for long launch windows that are more than just an occasional exception, that may be good enough to formulate a definitive answer.


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