The main V1 track is gapless. When you import footage, Premiere Rush automatically assembles all clips in this track next to one another with no gaps in between the clips. Similarly, when you remove a portion of the footage, the rest of the clips automatically align themselves leaving no gaps in the timeline. You don't have to manually align clips. The V1 track is lighter in color than the other tracks.
Clips placed on tracks V2-V4 and A1-A3 are associated with clips in the main V1 track, keeping your clips in sync.
More info here: https://helpx.adobe.com/premiere-rush/user-guide.html/premiere-rush/help/edit-timeline.ug.html