Allow me to bring to your attention a new feature designed to solve this very problem
Download Here By: @L. Vern , @KungCheops Special thanks to @gwennog and @jarcast2 A QoL modmod for controlling how automated workers construct routes. Requires VP EUI 4.6+. (Technically it still works without an EUI install but you won't be able to see anything as the plot highlighting is done...
forums.civfanatics.com
it allows fine grained control over what automated workers will do regarding road construction, but also coarse grained control to the point where you can just press one button to stop automated workers from building any roads at all when automated