Key is to make the second entry point 'unattractive' to traffic looking for a shortcut.

I already did most things like City Planner Plays just mimicking what I saw on Landsat images I used to study obsessively. However learning not to make what was functionally enormous cul-de-sacs from him was key. Always have 2 ways in and out. IRl its because of fire/emergency evacuation. Low population risk only. In game its because services function a lot better not having to backtrack so much drastically reduces traffic-if your road hierarchy is good. CPP helped me understand the how and why of it all.