well i think it depends upon the time you have spare with you ! But Submitting of sitemaps can be of daily, hourly, monthy or yearly but its good that you stay uptodate with google sitemaps by submitting it twice a week. Thanks
I have a plugin installed that sends an updated sitemap to Google every time I publish a new article. I would normally add 2-6 new articles per day. I have seen my articles showing up in Google searches by readers in as little as 20 min so I think it works very well. I also have another plugin that sends a ping to a list of blog search engines with every new article published as well. Ive seen my articles listed as fast as 10 min at Technorati.
I only submitted the sitemap once, after that I never update it. It's better to spend time in getting backlinks than updating sitemap. If you have inbound links, google will follow them and crawl your pages.
id say once every 3 days if you continually update the site. or once a week if you dont. or if you hardly every update then once a month. just saying it depends on how many times you update the site
it's better to have installed some pluging on your pc which automatically keeps on updating while you submit some article on the web...
Or set a program to run once a week automatically scanning, uploading and pinging Of course, if your computer is shut down during the night, that might be a bad idea