Apply effects to multiple video channels in Sony Vegas
Say, you have a video that has indoor and outdoor scenes, and also some other tracks. And you notice that indoor parts require brightness/saturation adjustment.

You cut your video into a sequence of scenes (Video Events), and you find it boring to apply FX to all/several indoor events, especially if they are cut into many places across your video.

I use a pretty simple technique to automate it.


Make sure all Video Events that need to have an FX stay on a separate Video Track, so that the track contains only events that do need the FX. Call it, say, "Indoor with brightness".
Let's complicate things and assume you also need some scenes to be pixelated. Place them into yet another track, call it "Indoor with brightness and pixelate". Apply Pixelate FX to this track.
Make a new Video Track, and call it, say, "Brightness FX Master"
Make both "Indoor with brightness" and "Indoor with brightness and pixelate" tracks to be children of "Brightness FX Master" track
Apply the Brightness FX to "Brightness FX Master" track




Pros: You set all FX only once. Modify it freely and you don't need to re-apply it.

Cons: Usually, you will have to cut through the tracks carefully because it's impossible to add a non-FX track in between two child tracks. Also, managing cross-track crossfades is often a difficult to accomplish.

Also, You can't partially apply an FX this way, e.g., Brightness +10 is always Brightness +10, there's no way to set its opacity=50% (effectively to Brightness +5). In this case, use Animate feature to dynamically change parameters of applied FX ("Brightness Amount", in this case).