A few years ago, when first trying to develop my own rail schema, I discovered the Modular Rail System by u/Opiboble (https://www.reddit.com/r/factorio/comments/6ijd8e/modular_rail_system_mrs_update_now_with_more_2lane/?st=j46i04kt&sh=b4d302fe)
Once the grid-aligned update for blueprints dropped, I went and updated the MRS book I had to be grid-aligned on a 58x58 pattern. This required some small adjustments to many of the BPs, and a small size increase in the BPs overall. Still, the effort was worth it :) The BPs have been designed to connect anywhere you place them down at, due to the grid-aligned nature.
I'm sure many of the signals aren't as optimal as possible, but it's good enough for my needs. I don't really use the Four Lane variant in the original post, but this work here could probably provide a good starting point if someone wanted to tackle it.