Video Track Masking
It would be fantastic to apply a mask or effect to an entire track. For instance, when cutting split screen videos, you could mask one track to the top half of your screen. Then any footage you put into that track would be restricted to the track's mask.
Then you could more easily work with different resolutions, reframing, and layout without worrying if your seam is going to be consistent across the video.
I know this is similar to this ask: https://adobe-video.uservoice.com/forums/911233-premiere-pro/suggestions/33869674-assigning-effect-to-video-track. But everyone in that thread just said adjustment layers, that was that.
Terje Bergli commented
Yes, this would be an excellent feature, but this suggestion is being split into several requests and we need to team up.
Put these terms into the search field ("video" "track" "effect" "adjust") and upvote similar requests.
Adding color grading or an effect to a video track would be a massive improvement. Adjustment layers, nest, master clip grade etc. will not do it as smooth in a larger multi cam setup.