Programming every board meant soldering wires to five tiny pads and removing them again. So I designed a jig in OpenSCAD: drop the board in, press, flash. Five spring-loaded pogo pins touch the pads from below; I measured mine at 16 mm long with 2 mm of travel, and the whole model grew from those numbers.
Then came a simple question: what actually stops the pins from falling through? Honestly, nothing but friction. The fix was to make the base tall enough to hold almost the whole pin, and close it from below with a flat cap that the pins rest on. The cap, not friction, now decides how far each pin sticks out.
I also built neat rims so the parts would line up by themselves, looked at what printing them would take, and pulled them out the same day. The screws line things up just fine. Sometimes the clever version is just the one that's harder to make.