The idea of “good support” varies greatly from host to host. Some respond to tickets in as little as ten minutes, while some might need ten days to fix an issue. And of course, response time also depends on the severity of the issue.
In my opinion, 12-24 hours is a reasonable response time for most issues. Critical problems should be addressed in no more than 6 hours.
If your host takes longer than this to get back to you, it isn’t delivering the support it should. I’ve seen hosts take as long as three days to get back to customers! It is unrealistic to expect instant gratification, but only fair for hosts to address issues in a timely manner.