I stop and resume renders quite a lot. I had some renders recently that run 3-5 days because I wanted some big versions. I did not want to lose the whole render in the last 5 minutes.
Also, I often leave a render running at night or when I'm otherwise busy, but interrupt the render when I want to use Vue interactively on another project. Then resume render again at night.
It's also a good idea to save the image itself when you interrupt the render, so that even if the machine crashes you'll only need to redo the unsaved part and composite the parts in post work.

Only once when I resumed a render it skipped a row of pixels, but it was rescuable by rerendering just that thin strip and compositing in PS.

Resuming render is invaluable!

"I paint that which comes from the imagination or from dreams, or from an unconscious drive. I photograph the things that I do not wish to paint, the things which already have an existence."
Man Ray, modernist painter
http://artpearl.redbubble.com/