I am building a sitemap file generator and have been reading about the various limits. (50,000 URLs per sitemap and 50,000 sitemap files per index file).
I have already been building this with the strategy of organizing my sitemap files similarly to how the links are organized on the actual site. However, I am noticing that in time I will likely need to restructure due to the limits mentioned above.
So, I am now thinking that alternatively I will store every possible link/url in a DB table and then just run a cron job which generates XML files, one per every 50,000 URLs I have. This approach is more easily scalable but also lacks any organization. I am curious if any SEO experts out there know if this matters to google, or if the URLs are all seen in the same light, and not by how they are grouped.
The purpose of a sitemap is simply to help Google fully understand the structure and layout of your website.
That said, as long as you are using a technique which effectively communicated to Google the layout of your site, you should be alright. Since you seem to still be communicating the right message about the structure of your site, this technique appears OK.
See here for more information.