I know that yes you should always use the Shop Manual and if you don't you are asking for trouble.
There is always some specification or technical issue or criteria that your lacking could destroy a critical component or system. I single handledly destroyed a 240D Manual transmission that way, by using Gear Oil vice ATF. There is always a dissasembly trick or twist that lies there clear as day in the Text.
But the other day i was adjusting my Volvo sunroof. Lucky enough I had the patience to stop by the Junkyard and practice on a car there. The service manual made no sense.
So at the junkyard I practiced taking it out of the car completely and putting it back in and studied the thing and did not have to worry about scratching Paint. When I got to the Yard I realized my Sunroof had been serviced badly by itrs previous owner and was missing key parts.
After doing it and going back and reading the service manual again, I was still confused. I have to admit a lot of things about the contraption were intuitive and elusive and hard to depict. And some techniques like holding two moving pins in during reassembly with tiny dabs of SuperGlue that wanted to pop out on their own until the roof was screwed down were things only Diesel heads could guess.
So sometimes I guess experience is starting to take hold. 99% of shop manuals are Critical but shop manuals are also as only as good as the writer.