The NMC generally accepts the seatime letters at face value. If the letter says 30 days, you get 30 days.
NMC doesn’t have time to look into the type of nuances and details that you discuss. If the Coalminer’s daughters at the NMC started parsing seatime letters for those details, routine license applications would take a year instead of three months to process.
Everyone has a modest amount of time alongside the dock, in the Anchorage, or at the shipyard. That’s expected and understood.