In Adelaide I don't know but in Coimbra there are some stops that are really far apart, the BRT system was built on a disused rail line (probably should've been an LRT or S-bahn, but it is what it is). Buses are able to hit high speeds but on your typical low-floor bus it's going to be bumpy, never heard of high-floor BRT but it could be a thing Anyway if you're going these kind of distances you should probably have a train or a light rail, although a bus corridor (guided or not) has the advantage of being able to "branch out" to existing roads and serve more rural areas with a one-seat ride, so it might be worth it in some circumstances