Execute ultimates should have an indicator when they can kill.

So after the Rek'sai rework(This champion that no one seems to know about) I decided to pick her back up and start playing her again. Overall I love her new ult and how it makes her feel like the landshark she is. However there has been something bugging me with her ultimate. Despite its high damage scaling and missing health damage I found that every time I chose a target in a teamfight either my team would kill them before the ultimate could hit, or it would just barely not kill them. I went around looking at other champions that have executes and noticed that ,, and all have an indicator when their ult can execute there target. Initially I thought that could use an indicator on her ult for purposes(I'm so sorry), but then I realized that also doesn't have an indicator. So as a little proposition that I believe would help clarity with such champions, I believe that it would be a great idea to have all execute style ultimates have a visual indicator as to when they can kill there target. So that there team and player know that they wont be wasting it. (unless the enemy has or other healing) Sorry for the wall of text, but I would like to know what you guys think of this?