Terminal blocks and din rails wouldn't be replaced by these I would think. The quality of some terminal blocks are so much better than others thou.
The Wago Lever type Nut would be good for Testing gear that gets hooked up many times, I had mine on a 24VDC supply that I use to test sensors.
A picture of some type test setup that was temporary. Can be used to protect wire ends too, I see a pink wire open at bottom. no indicators
on, so I think I got a picture of it during his setup of what ever he was doing. That will not have been left like that.
Found this interesting picture, I took picture so show someone (unskilled) added a blue and grey wire to supply. He didn't use a wire label and ferrule. Blue wire would have not been in documentation too. That wire got torn out or done correctly. Probably why I took picture. Note the red jumper blades on the Relays, same parts for Terminal blocks.
When the blue wire was added, did he check the current draw on supply to make sure it was ok? Doubt it. 3A of 5VDC power isn't much. The blue wire also skipped the fuse for the supply output.
Leaving them on a project I would think Motors Junction boxes mainly. Getting rid of solid wire and stranded wire in a typical screw on type nut would be my other thought as mentioned before.