For our client: We monitored everything on a daily basis. If something came up, which needed to be fixed, we were quick to implement it with the development team at the business. We also rolled out numerous campaigns multiple times as they worked effectively the first time around in generating significant traffic so it was second nature to do the same thing twice.
The fee structure is both a filter against superfluous submissions and a revenue generator. Typically, the fee covers an annual subscription for one webpage, which will automatically be catalogued on a regular basis. However, some companies are experimenting with non-subscription based fee structures where purchased listings are displayed permanently. A per-click fee may also apply. Each search engine is different. Some sites allow only paid inclusion, although these have had little success. More frequently, many search engines, like Yahoo!, mix paid inclusion (per-page and per-click fee) with results from web crawling. Others, like Google (and as of 2006, Ask.com), do not let webmasters pay to be in their search engine listing (advertisements are shown separately and labeled as such).