Let me try to clarify I do understand what you are suggesting, but that is not my issue. I know about audio markers and use them wherever it makes sense. But sometimes you have to adjust the length of a single slide without all other shifting as well. And having to use audio markers for that seems not the best option.
AV Wings for example gives you the option to change the duration (or entry point) of a single slide with or without affecting the others by the use of a modifier key while dragging the slide duration.
I made a shot screen recording that would hopefully illustrate my point better > Screen Recording
My goal is to change the “IN” point of slide 21 by moving it to the right (thus of course lengthening slide 20) but NOT changing the entry point of slide 22 and following. The way I see it there is no easy way to do this at the moment.
Case 1 in the video > by adjusting the IN-point of my slide (dragging it to the right) the transition is at the right position but all succeeding slides move as well and are thus out of synch
Case 2 in the video > changing only the transition dosen’t effect the timing of the rest of the slides, but the entry-point of slide 21 is still not correct
Case 3 in the video > the only way to achieve my aim is to move the entry point of slide 21 and then readjust the length by moving slide 22 (and thus all succeeding slides) back to the left to get them in synch again
Case 3 might not appear to be much effort but it is a dangerous workaround because one can easily forget to readjust the rest of the slides. Audio markers a great tool but not what is needed here (or simply too complicated to accomplish a relative simple task).
In my opinion the solution would be a simple way to change the transition point between two slides (in this case between slide 20 & 21) without affecting the others. Again this in “AV Wings” this is done by using a simple key modifier to switch between the two behaviors (I do believe Premiere and other video editing software have a similar approach for blending clips).