We have a live server that's being hit hard so we're tying to optimise everything we can. We ran the MySQLTuner script on it (http://mysqltuner.com/) which tells us we should set a value less than 28800 for wait_timeout & interactive_timeout. There's a lot of possible numbers to choose between 1 and 28800!
I looked up the meaning of these variables in the MySQL documentation but that gave only a very basic description and no guidance of choosing a value.
Is there a value that's considered a generally accepted best practice? And what would be the likely outcome of choosing a value that was too low?