The gas seems to be on all the time, Haldi, even when they are removing some to add to a curry?
I'm sure you can appreciate the significance of this question though?
As SS says, if they leave the heat on, the character of the base will change over time.....and if they leave the heat off, the character of the base will change over time....or will it (maybe it's the main dish that varies, more so, in this case?)?

I guess, with other types of cooking, the stock is added to the main dish cold isn't it?
Sorry, going off-topic here...but an interesting issue....