Then project is done and you need to change something its really hard to replace, most time no need to overwrite, crossfade working only left and i think no need to insert. So all these very good to create something, but most all of them destroy timing, then video project is done and you must replace some video with another video.
I think you must focus on not moving any existing video in project and just after this must be option- " maybe you want to move". Too many checkbox must be checked in order to prevent any timing move.
I even creating 4 and more rows of video , because thats the way to prevent moving video, i can lock them. But in this case i sacrifice about 4 transitions.
I making video clip and then audio and video is adjusted its VEEEERY HARD to change something in the beginning. If all in 1 line i think its impossible to change and not move rest. Please focus on not move timing of all the rest video in any case and only after that small option " maybe you want to move".
And let that focus be easy. Let's say it locks all lines automatically, but most problem again, then all video in 1 line.