How often should an automatic require manual winding?

[bsandiford]

I wear my rolex (with 3185 movement) for 5 days before it stops. I have it wound (around 40 revolutions of crown) and then wear for 12-14 hours per day. By the morning of day 5 when I come to put it on , it has stopped. Any views on whether this is normal or whether this indicates some servicing is needed??