X days are known rest. The scenario we are discussing primarily concerns when a pilot has a single X day between 2 blocks of reserve. So a pilot with 2+ X days will automatically have a known, prospective 30 hour rest period going into multiple X days. All the CNO does at that point is try to move the rest to start 6 hours sooner. For a pilot with 2+ X days all the rest really might affect at that point is their legality for a GS on those X days. The company's system doesn't differentiate between LC going into a single non-golden X day or multiple non-golden X days. It will auto CNO you at 0600 on LC the last day to assign rest at 1800 that night.

Just to reiterate, this whole issue only applies to going into a non-golden X day. If you are going into a golden X day or VAC day you are auto released into rest at 0600 and that rest is known and prospective and no notification from scheduling is required.