Google: Persistent 5xx Result In Slower Crawling But Won't Say How Many URLs Required

Google's John Mueller said that persistent 5xx error responses to Google's requests by your server would result in Google slowing its crawl of your web site. John wouldn't say if there is a specific percentage of your site's URLs that are required or a specific number. But he just said if Google sees persistent 5xx errors, Google will slow how it crawls your site.