The question is not so much how much you work as how good are you organized? What percentage of experiments goes wrong and why? How concentrated are you when you are working? Have you read enough literature to really know what you are doing? How good are you/the people in your lab at trouble shooting.
Our other PhD student is working her ass off (can I write that?), but it is getting her nowhere, because she won't take advice from the postdocs (who are getting royally annoyed after answering her questions- just to find out she's not listening to their advice anyway), she changes methods without any reason- although the original method works fine, and generally makes many mistakes.