Google's John Mueller said on Reddit that Google uses XML Sitemaps like an energy drink. John said "All sitemap files of a site are imported into a common, big mixing cup, lightly shaken, and then given to Googlebot by URL in the form of an energy drink."
Google has always recommended you use XML Sitemaps for sites that need better indexing. Smaller sites probably do not need them but they are easy enough to make for smaller sites that is probably worthwhile.
John went on to add "It doesn't matter how many files you have. If you give the last-modification date (which you should), then you just need to make sure you're giving the same date for any given URL across the files."
So if you need a boost in terms of helping Google discover all your pages, then try XML Sitemaps as a boost.
Forum discussion at Reddit.
