When extending a road and after building a new milestone, you should automatically be able to place the next milestone. No more opening the GUI and extending after building every new milestone, except for occasions when you need to restock building materials or clear some trees/dirt. Just build a milestone/signpost, and automatically you're placing the next one, and so on.
Bonus: The next milestone's ghost placement preview should be initially rotated identically to the previous one, not fucking facing towards the player. So annoying.
Bonus: Some sort of message/indicator if the path between the two milestones is blocked or not, preferably before placing it.
Edit: Someone suggested even drawing a vector between the travel points of each marker, which would visually explain to sprucecaps how roads work and become interrupted.
Bonus: Just remove travel weariness from roads already