The general answer is that it depends. On my servers I have
kept it to 30 seconds as default. But in the scripts which I know
will take long then I reset it to whatever number I want at the
beginning of the script.
On servers with low traffic, the timeout won't make big
difference, but on busy servers, it is recommended to have the
script finish its job asap so it could handle more users. So having
the shorter timeout is recommended on busy servers.
HTH,
Ketan