When I shot medium format, I tended to shoot an entire roll on one subject, experimenting, playing around more with composition, filters, and even exposure. Sometimes I would start with an overall view of the subject, then begin moving in closer to what attracted me to the subject. So in that regard, I would agree with your "sketches" simile. I usually only expected to get one "keeper" out of the roll.
Now that I am shooting 4x5, I find that experimentation is done through the ground glass, but without exposing film. When I expose film, I expect to get a negative from which I can make a finished print. Sometimes it works and I get a picture that I am willing to show to others. Sometimes not.