Alright so this is what I am wondering? What determines how much your site gets crawled and index on Google? Does it have anything to do with the amount of searches there are for your site on it?
If you want to get more pages crawled and indexed on Google you should include on your linking strategy links to internal pages, and if from this pages you can link to your site map will be better. This way you will give more ways to Google spider to discover and index more pages. Try to make your sitemap 1 click away from any page. This has work for me...
if you need your site get crawled often you need to have your link all over the place such as high PR forum, high PR blog, social networking and bookmarking site. if you don't do that and you site are static page your site will be likely to be crawled once a month.