Push-Wires (also called Jumpers) seem to pop out all the time. I think it has to do with wire mass (in motion) overcoming spring-clip retention force.
A few observations on Push-Wire types;
- Homemade have stripped ends, Manufactured have pin ends.
- Homemade are cut to size. Manufactured are fixed size, usually longer than needed.
- Either type's connection may fail in (Vibration, Impact or Redress) situations.
However, if you insert a Single-Sided Header into a Breadboard, you can wire-wrap to its pins. That eliminates flimsy jumpers.
The square .025 posts hold tight because they're close to the max wire size spring-clips can accept. Here's a picture...
Since multiple pins are holding the Header, its well secured. And since #30 wires are low mass, they're more tolerant of Impact and Vibration!
Above the spring-clip, wrapped wires traversing squared-pin corners are making gas tight connections. Wire surfaces exposed to air oxidize over time, but gas-tight parts (at multiple corner points) tend not to oxidize. Therefore the wrapped wire connection remains viable for years.
The Header pin inserted into the spring-clip, is likely to resist oxidation too. Its (near maximum spring-clip force) connects with flat sides of the pin-post. It may be that flat pin-posts present more surface area to spring-clips than a round wire.