I'm currently working on a news website project. It has a lot of categories, subcategories and links. When creating the sitemaps for this project, I planned to create an Index sitemap that lead to the categories sitemaps. To avoid the 50000 urls marks, I intend to create sitemaps weekly. This will result in 52 sitemaps per year per category.
What I want to know is, if I have (for example) 10 categories I'll create 520 sitemaps over a year. Is this number a lot ? Should I approach this problem in any other way ?
There is no limit on number of sitemaps. As long as each isn't more than 10MB and 50,000 URLS. Address to each sitemap must be in one and only one sitemap index file.
This site has more information (http://www.sitemaps.org/protocol.html#index)