The UK uses a traffic system called Scoot (Split Cycle Offset Optimisation Technique) so the same overall principles apply whatever town or city you live in.
Edinburgh has roughly 300 traffic junctions of which about 50-60 are junctions where the green man comes on automatically. In the jargon this is known as "walk with". It is usually where a one-way street connects with another road. The green man comes on whenever the red traffic light shows. At night this might change but during busy times the system is automated.
The maximum wait time for a green man in the UK is set at two minutes, says Martin Low, transport commissioner for Westminster City Council.
That can feel like a long time.
Low wants councils to help pedestrians to cross even if there is a red man. Instead of constructing barriers, Westminster is putting in "perch" islands in the middle of roads to allow pedestrians to get across.
And here is where the UK differs from some other countries. The British pedestrian looks to cross whatever the lights, merely checking whether any traffic is approaching. (The law is on the pedestrian's side, except on motorways, certain other roads...)
There's a number of infuriating junctions I have to pass through which I'm sure the button has no effect and you have a long wait to cross while cars are prioritised through.