Put the request in to drop days at least 20 times. All will be denied.
Then call CRS.
Aske the scheduler to EXPLAIN why it won't be dropped.
Drivel and BS will ensue ... the computer controls it Mr. Pilot, I can't do a thing.
Then, since you won't be satisified, ask for the manager. Same story.
Then try again to drop via CRS.
Magically, it works. Sometimes.
If you try to drop too far out, i.e. more than 4 days, it won't happen.
Of course, we do have a sick bank in the event you take an unfortunate tumble down the stairs or fall off a ladder. But that's pretty rare.