Here is a very famous and very beautiful prelude by Chopin:
What's so extreme about that? The piece starts rather conventionally in D flat major with an 8 measure phrase answered with an 11 measure phrase, then the first phrase is repeated. So far, except for the expanded middle, this is pretty ordinary. But Chopin noticed that in the accompaniment there was this repeated A flat note that was present in every measure except for six measures in the middle where it becomes a repeated F. That seemed the most interesting thing going on, this obsessive repetition of, almost, a single note. So he continued the piece, moving to the key of C sharp minor. C sharp is the same note as D flat, of course, just spelled differently. This section of the piece is twice as long as the first part and now G sharp, the same note as A flat, is repeated over and over and over in every bar. Finally, the opening 8 measure phrase in D flat returns, with its repeated A flat note. This is the kind of against-the-grain kind of thing that Beethoven might have done: start by writing a rather ordinary piece, then realize that the really interesting thing is a detail of the accompaniment, so keep focusing on that until the possibilities are exhausted. Rather extreme... This device, of repeating or holding a single note while the rest of the music revolves around it is call a "pedal" or "pedal point" because it was typically used on the organ where it is very easy for the foot to hold down a single note in the bass while the hands do something else.