"Writing this makes me think it deserves a footnote / warning: if while reading these remarks, you feel that modules -- or anything else I'm going to mention here -- are a "simple thing" that's easy to get right, with obvious right answers, I'm going to suggest you're likely suffering some mixture of Stockholm syndrome induced by your current favourite language, Engineer syndrome, and/or Dunning–Kruger effect. Literally thousands of extremely skilled people have spent their lives banging their heads against these problems, and every shipping system has Serious Issues they simply don't deal with right."

Amen!