Can someone share the details of Spirit's Drop To Zero policy? I've heard it's great for QOL. Are there any limits on dropping on certain dates (holidays, low reserve coverage, etc...)? Can you drop to 0 hours in a month, or are you required to pick up to a minimum threshold? If you can drop to 0 hours in a month, are there limits to how often you can do this in a year? What other airlines offer this? Thanks in advance.