You can drop to 0 with no contractual minimum at UAL. I'm not sure how deductions work for things like insurance as I've never been taht low myself at the end of a month. In recent months on the WB the whole month has been green and I can drop or swap whatever I want. It's harder to do in practice normally than it was during my time at NK.

I still have never had to call in sick for time off I needed that I had scheduled over. With bad day/worse day language, swaps or another pilot picking it up off me, I've been able to get rid of numerous trips.