Station Spacing

Spacing between bus and train stations has always been a problematic decision for me. That is why I'm asking you how far apart you place stations. Specifically...

Distance between bus stops: (rural, suburban, and urban areas)
Distance between tram/light rail stations: (suburban and urban)
Distance between subway stations: (suburban and urban)
Distance between train stations: (rural, suburban, and urban)
Distance between High Speed Rail stations: (suburban and urban)

are you talking real life or in SC4?

In SC4.

In general, I don't care about the spacing. At long the Sims get to their destination as fast as possible, I'm happy with it. But of course, I don't place such stops/stations too close per direction.

Distance between bus stops: Generally, in urban areas, there is one on every block. In rural areas, one in the town centre.
Distance between tram/light rail stations: Generally every 2 or 3 blocks in urban areas, close to the local shops in suburban areas.
Distance between subway stations: Generally every 2 or 3 blocks in urban areas, close to local shops in suburban areas.
Distance between train stations: Generally there is only 1 in each town/city, except in Redding City where there is also a station at the airport and one in the Eastern suburbs. Yorke also has an additional station at Olympic Park.
Distance between High Speed Rail stations: Arcacia doesn't have high speed rail, but if I did, there would only one station in each major centre.