Anyone work for an agency that bills by time?

How can this work for SEO estimating?

[Eljaybe]

I am struggling trying to predict the number of hours an entire 12-month SEO campaign (including link building) would take me to complete. Many agencies bill clients for their time spent on projects, but it seems like it might not be a good idea with an SEO project. I understand it depends on the number of pages you intend to optimize, and other conditions, but can anyone give me some good advice? We all know how much time it takes to do SEO, and agency time could add up quickly, so what is the best way to charge for this service? I don't want to overcharge clients for SEO, and I don't know if I can find a way around billing by hours. Let's say you intend to optimize 5-10 pages of a client's site. How much time would you spend on keyword research, competitor analysis, etc.?

[Stores]

The road to hell is paved in billable hours.

Charge them based on the value you provide.

[paladin]

What I have seen done (and usually works) is to set up packages of hours. Almost like a lawyer or other professional services consultant. X hours of work per month for Y dollars (or whatever currency you wish to be paid in).

[Eljaybe]

Stores- Very funny! I think value is more important than hours, but unless we can bill on a per-project basis we are stuck trying to stay within budget by billable hours.

Paladin- I like the idea of packaging hours per month. However, we would propose a 6 or 12-month campaign for most clients which means hours could be higher in month 1 and 2 rather than month 5 and 6.
Also, we have had those "special" clients who just don't understand SEO. They want things done their way, they only want certain pages of their site ranking in the search engines- nevermind that more pages equals more site traffic! It's a lot of back-and-forth and unnecessary meetings with these type of clients. We have gone over budget in hours spent on "special" clients and there's no way to really know which campaigns will run smoothly and which ones will get dragged out because the client doesn't "get it." It doesn't seem fair to charge one client more than another for the same campaign just b/c we assume they will be a "special" client.
I know most time is spent upfront with consulting, positioning report, strategy outline and keyword research. So, to go back to my original question, how much time should you estimate to spend on an SEO campaign each month? Let's say you are optimizing 5-10 pages.