The problem is this will make your site unusable for people on slow connections. Some people have internet connections that take seconds to connect, and nothing the site does can make that faster.
Not every app is forced to support terrible connections. We definitely had issues with hung operations until we had a timeout, though there was some disagreement about failing “fast” (10 seconds is “fast”???) vs hanging inexplicably for much longer, but not forever, periods of time.
Edit: when REST calls occasionally failed after 10 seconds, rather than hanging the UI, the support calls stopped. 2 or 3 people a day had to hit submit a second time. They got over it, as opposed to reloading the app/page. This was the most cost effective way for us to handle this.