I have from time to time, one of my cases which at start-up does not light up the -12V led, I turn it off and turn on it again and everything is fine.
Fortunately, my DIY panels are not dimensioned to the nearest mm, I have small small slots between the modules, and I carefully check all the power leds by these mini slots each time they are switched on.
In any case very good idea, much more practical, if I had space I would put it everywhere 