Totally blind person here. I haven't used echolocation much in my life, except for the standard wall/door detection tricks, of course. I've met a very small number of people who do it successfully, though. One guy I know is a near expert. He lost his sight like 4 years ago and he alrady learned it on a pretty advanced level. He taught us to detect things like glasses on a table and tell where they are. The class was only like 3, 4 hours though, so I guess it's just the tip of an iceberg.