Well it depends you say-and I agree with you-It varies depending on the page, how complex it is, the style, how much content, graphics used, effects etc. So let me eliminate some of the variability, and ask, how long would you say it takes to design this specific page http://www.ehow.com/.
The reason I ask this is because I've been doing some freelance design for a few years, but am thinking of looking for work at an agency and wondering what an average workflow might look like. For me personally, I'd say that design might take 8-12 hours (and that would be going full throttle); maybe someone could give me a bit of a sense of what a common expectation might be for an agency. Thanks.
edit- branding,discovery or code not included; so just for design phase that stretches from wireframes to finished psd.