The workflow of creating bus routes is very similar to what you discribe in JOSM.
Personal opinion: I think we shouldn't map bus routes manually for multiple reasons:
- Modern public transport companies publish their GTFS feeds usually with a compatible license. There are projects going on to import them to OSM or to combine them in end user applications. There are a lot of usable examples for the latter already, e.g. https://transitous.org/
- They are hard to verify on the ground, you have to travel on the bus in question to make sure it actually uses that street, not the next one, if there is no bus stop nearby.
- Long relations are prone to bork themself. Just check the invalid bus routes on osmi, most of them have a gap, they are hard to fix and maintain. Just zoom in anywhere: https://tools.geofabrik.de/osmi/?view=pubtrans_routes&lon=16.33692&lat=39.75409&zoom=2&baselayer=Geofabrik+Standard&overlays=ptv2_routes_invalid%2Cptv2_error_ways%2Cptv2_error_nodes copy patste the link if it's not working:
https://tools.geofabrik.de/osmi/?view=pubtrans_routes&lon=16.33692&lat=39.75409&zoom=2&baselayer=Geofabrik+Standard&overlays=ptv2_routes_invalid%2Cptv2_error_ways%2Cptv2_error_nodes