Thanks for posting, that is very interesting! Confirms some of the things I've noted over the years.
Best bit of advice by the way that mom ever gave me, and that's how she's been doing it for years: measure the pattern befor you copy or cut it, so you can make adjustments. I tend to just copy the pattern, no matter if it's vintage and modern, so I can make necessary adjustments right there - and if it works, I keep that copied pattern in the envelope.