Search Engine needs sitemaps for faster site response.
If you set your sitemap and robots in your root search engine will prefer to read only what you decided.
If your site are small or middle sized based on static pages you don't need sitemap but for CMS,dynamic and bigger sites will be better to find a way to build your sitemaps daily and ping search engine.
We will make sitemap frequently based on all occasions and ping search engine dynamically.
We will use all search engine webmasters tools.