HI Kyle,
The process you described is similar to what happens here. I have had an updated website (Theme and functionality) done as of December 2011, it is still being approved through various channels. Technical information must be accurate and approved by engineering, legal wants protection and marketing wants SEO godly-ness.
I'm not sure what particular job you are trying to fill within this company, if its SEO or Web Development or Content / Copywriter or all three. I think the best solution is to help your client understand exactly what you do and what results are obtained. If they don't understand the process of publishing content then you may be responsible for teaching them, so you can actually function without them harassing you.
Me, I'm mostly the web developer here, but also do some marketing work. When we get technical mumbo jumbo back from the engineers we are responsible for staying true to the jargon but still using our keywords and SEO optimizing the information and presenting it in a pleasing manners to our customers.
The short answer is your client must understand the process, what your role is. They must also understand that your service is contingent on certain needs that you don't control. They have to share the responsibility of making things happen.