I map on the basis of adding pavements when they detour away from the road edge and curb, connecting that back to the road for routing benefit. Just remember yourself to adjust sidewalk tags on the road to separate value or as appropriate when doing such micromapping. Those sidewalks tags already enabled routing agents to optimise for pedestrian safety. Adding partial sections with dead-ends isn't of much use to anyone, aside from more precise distance measurement I suppose. I'm all for it at complex intersections though with railings or other safety mechanical interventions.