This is pretty much unrelated to the discussion earlier on (which was about the interaction of different flow control mechansisms). But nevertheless one answer

This is pretty much unrelated to the discussion earlier on (which was about the interaction of different flow control mechansisms). But nevertheless one answer that tries to clear up some misunderstandings: You can reuse connections with every HTTP version up from HTTP/1.1. The main difference between HTTP/1.1 and HTTP/2 and /3 is that you can't make concurrent requests on a single connection with HTTP/1.1, but you can with /2 and /3. For how long a connection will stay open after a request will be determined by keepalive settings on the client and server side. All HTTP versions up from 1.1 allow you not to use a connection for 30s and then make another request.