The ability to drop trips is a moving target run by a plotter that takes inputs on forecast reserve coverage and trips already, or forecasted to be, in open time. This is why trips that touch weekends are tough to drop; even though reserve coverage is higher, they expect additional trips to be called out sick so they lower the value. It’s also why trips may turn green initially when TTOT opens; it’s not the lights are “confused”, it’s that the plotter values allow trips to be dropped right away, then it locks down those numbers as people start dropping trips.

This is what caused the Christmas boondoggle – a human input incorrect values to the plotter and it allowed everybody to drop everything until the company caught on and locked down TT to correct the values.