[plt-scheme] Behind the scenes, is everything running using continuation passing style?

Someone told me the other day that behind the scenes every Scheme
program is running using CPS, you just don't see it explicitly in your
code.

I took it then that when you call call/cc, you are simply exposing
access to the current continuation that is going to be called after
the current function has finished evaluation.

Behind the scenes, is everything running using continuation passing style?