I've got this :
Auto Restart : Yes
Auto Fix 503 Error : Yes
Graceful Restart Timeout (secs) : 120
The gracefull restart of litespeed is done with a few seconds. I'm pretty sure I did not touch this setting even though it says the default is 300.
I don't think I'm hitting the 120 second timeout as the whole procedure takes less than 20 seconds before PHP comes back.