Same as we can look at a page full of routes, e.g. from destination view, select all of them, and change the prices for every one of the checked routes with a single action. Many of the default cargo splits are not terribly accurate, e.g. 60/40 when there's only light cargo demand. I assume this is because it's 1956 in-game, and the demand split will be quite different in 2006. But it's a lot of clicking when you notice the 0% CS LF and investigate why, and then need to edit 21 separate routes (3 daily on a 7 day schedule) in 21 tabs.
21 tabs only? You lucky man! :laugh: