I'm not sure if it's an RFC or if each resolver is going to have it's own default.
Typically a resolver will query all the nameservers in order with a low timeout at first. Then it will increase the timeout and query again unless it received an error from the DNS system.
But according to DNS and BIND, 5th edition here is how timeouts work in BIND. BIND tends to be the reference implementation of DNS. The following is how bind 8.2.1 and later behave.
If only one nameserver is configured it will query it with a timeout of 5s and if that timesout then a second query will be attempted with a timeout of 10s. Then if that fails a hard failure will be returned.
If more than one nameserver is configured then it will query each of them in sequence with a timeout of 5s. Then it will loop back through the nameservers in order again with a time out of 10s for the first nameserver, 10/2 for the second nameserver, and 10/3 for the third nameserver. If all of these time out then a hard error is returned. With 3 nameservers it could take up to 33s for the lookup to really fail. Of course most of the time the DNS system either gives you an ip address or a lookup failure before this happens. So I would only expect this to happen if your internet connection is down.