Sorry, I should have been clearer. Going down a hill on a normal road, I will put the car in whatever gear will keep the car below the speed limit but when on a dual carriageway and already at speed, I often coast down hills. :shrug: it saves on fuel
Going from 4th to 2nd would suggest either a surge in revs immediately after the change or that the car was close to stalling before the change. I have always tried to keep the revs more or less constant and use the gears to control speed rather than the engine or the brakes. This improves fuel economy.
As for coasting up to junctions, so long as the driver is ready to brake, he is being more fuel efficient in allowing the momentum of the car to reach the junction rather than continuing to provide unnecessary fuel to the engine.
BTW, I have been driving 22 years and passed my test first time (FWIW, since the test was much easier in those days) and have also had advanced driver training from the police. I'm not saying that makes me a better driver than other posters but I do have a lot of experience.