Dave always says he hopes our projects fail (at first), and as luck would have it, I had one of those good "learning experiences" this weekend. I had prototyped a simple little 555 timer on the breadboard, which is intended to be the clock signal for a Z80 CPU. I wanted to move it to something more permanent and make it adjustable, so I grabbed two 50K pots, the 555, the cap and some jumpers, a piece of protoboard, and started soldering!
At the end, I plugged everything in, and.. crickets. Nothing happened.

And so I got to spend an hour debugging... continuity tests, resistance measurements, voltage measurements, probing different parts of the circuit, etc., etc.

And in the end, I measured the resistance between two pins (2 and 7, IIRC) and expected it to be around 45K, and got 90K instead. Aaahaha. Something wasn't right around one of those two connections. And finally, with enough focused physical inspection, I found a wire that looked a bit suspicious. It was soldered in place, but it appeared to both *not* be in contact with the pin it was supposed to be tied to, and possibly had a solder bridge to the wire beside it. Uuugh.

So I yanked that out, temporarily jumper clipped it to the appropriate pin, and LET THERE BE LIGHT (blinken LED's anyway).

The moral of this story... Heck if I know.

But debugging a circuit that doesn't work is definitely an interesting experience because it forces you to think through everything, trace every part of the circuit, understand what the voltage / resistance / etc. is supposed to be at different points, etc. So maybe Dave is right to hope that things fail at first.