wvmarle:
And even those jumpers do not guarantee a good connection... They at least make for a rather tidy breadboard, which is a plus in itself.
Once they work, it takes a lot to change that quicker than corrosion might eventually do.
I have used them, they're not PCB solid but they work for weeks IME.
The resistors and components on the board are more likely to break contact, PCB has no such problem but not so good for prototyping.