I actually had a project where i was given a) Prototype PCB for driving a pump (status unknown, no software for the MCU) b) A badly done schematic with no proper functional delineation c) Gerber files and asked to make it all work. I had to quickly ramp up on basic Electronics (am a software guy with no EE/Electronics background), learn to read the schematic, identify the inputs/outputs, map them to the requisite pins on the MCU and program it accordingly. While i did write the MCU firmware and got everything to work by myself (pat on back :-), the process was frustrating. No doubt much of it was standard "learning process" due to my lack of knowledge/experience but i was distinctly annoyed at my difficulty in understanding the schematic and mapping it to the components on the PCB for effective debugging. And of course, some of the component values on the schematic did not match the ones on the actual PCB leading to more painful debug sessions. It was "trial by fire" and i am happy to say that i passed, if i do say so myself. But still a very long way to go to catch-up with the industry professionals :-)