Most of the time my sketches are in preparation for finished pieces. In other words, they are rarely an end in themselves. It is only occasionally that I have been commissioned to do a 'sketch', apart from the hundreds I have produced for free at conventions over the years.
So, usually, my sketches are somewhat rough around the edges - incomplete as articles for display. But, when I do find one worth saving, as opposed to hitting the bin in a crumpled ball, it is a nice reminder of how nice just pencil is as a medium.