For the past week or so, we have been on a mission to figure out if Google intentionally removed the quota message in the Google Search Console Fetch as Google request indexing feature and if so, if that means Google removed the quota and limits to the number of URLs you can submit to Google within a specific time frame.
Yesterday I pointed out an error message after I tried submitting too many URLs to Google via that method.
Today, Google's John Mueller confirmed on Twitter that "there are still limits."
John wrote:
Yes, there are still limits. I'd really aim to use the more scalable approaches (like having a crawlable site, sitemaps, etc) instead of trying to fudge-force indexing manually.
— John ☆.o(≧▽≦)o.☆ (@JohnMu) February 13, 2018
So there you all have it - there is a limit.
Forum discussion at Twitter.