Many years ago, I was a product manager at a business-consumer electronics company developing some pretty leading-edge display equipment. Prototyping back then was a long and painful process. A PCB might take a month or two to arrive from fabrication. Parts had to be sourced by digging through massive catalogs and then hoping that what you needed would be on the companies approved vendor list. The whole process was a bear.
Well, the soldering up part wasn’t always so bad – unless you were the poor soul tasked with wire-wrapping or hand soldering the prototype.
Based on how difficult and expensive a board spin was back then, common practice was to just mod up the boards, even in production. Any given PCB might have a dozen or more cuts and mod wires. Those changes might not make it into the PCB for months. These days, though, you can get board fabbed overnight, your parts delivered over night, and when you have all of those parts and PCBs, you can get them assembled overnight. I suspect that increase in speed is the major reason mod wires seem to be nearing extinction these days. (note that Screaming Circuits didn’t build the board in this picture. It’s from my personal collection)
It may not seem cheap to pay to have someone respin a board so speedily; especially when set next to hand soldering. But when compared to the cost of idle engineers waiting for the next rev, the cost of adding mods, the reduced reliability from having mods and the additional manufacturing time caused by modding a board; today’s quickturn parts, fab and assembly options can end up saving gobs of time and money in the long run.
There are more wires in heaven and earth, Horatio, than are soldered on your PC board.