It was a holdover from when line bidding was a thing with no real way to avoid a bid line without hitting vacation. That’s why it was a feature. PBS doesn’t have that issue so why should there be an expectation of being able to intentionally bid a trip that is going to go get dropped because of vacation? While I agree that a vacation day should pay at least min day of 5 hr (5;15 I believe under Upa23) to get the add pay for a vacation day and get trips dropped with pay is an unrealistic desire.