What benefit is there to splitting your XML sitemap?

I've looked at different competitors and found a few interesting things, one being a competitor split their sitemap into two, one being all pages and then the other being just 'resources' (as in blogs and so on).

I've also seen sitemaps split into multi-language, I have a website with 4 languages and at the moment we hreflang them. But would a lang sitemap alleviate that? As in if you had a sitemap for each language? instead of one big sitemap

Thanks,