Set the Wayback for 1980.
People were making stuff in garages - literally - all across the country. (Some did a bit better than others though :)
Nobody really knew what they were doing - it was simply 'try it and see' stuff.
Four layer boards were unheard of.
Ground PLANES? Or sorry - plains? Whazat?
You shouls have seen the propotype Fergeson Big Board. Heavy ground wires twisted all over it like a Faraday cage.
We used heavy copper to get some metal in the (filigree) ground traces so the boards would work at all.
These days, it's different.
You have all the experience of the past as a starting point.