How long does it actually take to extract tea compounds from leaves using the boiling method?
I agree with the above comments that it really depends on the tea. The best way to find out is to boil the leaves let's say for 5 minutes in not too much water, then strain out the leaves. Now boil the leaves again for 5 minutes in fresh water. Does this second boil result in coloured tea liquor? Then this confirms that boiling it for more than 5 minutes is worth it. If so, then go for the next 5 minutes boil it for the next 5 minutes and so on, until you can confirm that you can't get any color and flavour out of the leaves.

Let me know the result!