It would be for some but then I did leave the brightness-up simply incremented 5%. So going up from 50 is easily resolved but then so do your scripts.
So might as well use them.
In that sense I found that holding the key indeed keeps the script going down or up, so that's nice.
What I did on my machine is add a last line to the scripts to show which step it is:
yad --no-buttons --undecorated --text=" <b>`brightnessctl -m i | awk -F',' '{print $4}'` `brightnessctl g`</b> " --center --timeout=1 --image=preferences-system-brightness-lock
Which shows the current setting for 1 second and when holding the key, it updates real-time.
I agree, but I would add the yad pop-up. It makes it all feel more responsive.
I do find that "brightness-elive up" in the same settings is too slow. Use case is more likely going into open sunlight and wanting the brightness as high as possible and as fast as possible.
I personally would stick to +5% overall in that case.