Maybe it will be helpful to explain how Premiere worked many years ago, which was how most editors worked at the time, using A/B editing. You would have TWO video tracks, A and B, and between them, a Transition track where effects would go. So, if you wanted a dissolve or wipe between two clips, one clip would be on A and the other on B, and looking at the timeline, the end of Clip A would OVERLAP the beginning of Clip B. If you wanted a 1-second transition, the "overlap" needed to be 30 frames. And then the Dissolve was dropped between track A and B, at the overlap area. Premiere Pro now uses single track editing, and believe me, when I updated years ago, I went through the same learning curve you are! Was hard to get used to. Butting two complete, untrimmed clips end to end, there is NO OVERLAP, so no way to make a transition between them. Therefore, we must trim the end of one and beginning of next, and then that "unseen" footage is available to create a transition with, think of it as unseen overlap. Thanks Jeff
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