Yes but as Eliezer said the work expands to fill the time. So if you cut the time correctly, you just cut out the useless work and don't give up any competitive advantage. This is how large corporations can lay-off 50,000 people without falling apart. Sometimes that means giving up products or markets, but more often it means a haircut across the organization - e.g. trimming the fat. At first the people left are paniced about how they will get everything done without all these resources, but what really happens is priorities get clarified and some people have to do more work during the day instead of reading Less Wrong. The same thing would happen if the work week were reduced, although management's job would get harder as Eliezer points out.
From Mike Darwn's Chronopause, an essay titled "Would You Like Another Plate of This?", discussing people's attitudes to life:
Conclusion, graphs, and references in article. As usual, I recommend reading Chronopause.com as Darwin has many good articles; to quickly link a few: