It does save quite a bit of time.
Let's say your GP spawn is 500 and you are working on HS. If you wait until your faith is 490 and pop the HS, your new threshold is still 750 (or whatever it is) so you are still 260 away. For simplicity lets say you get 10fpt so that is 26 turns. Starting back at 0 faith, you then get another in 1000 faith/100 turns. 3 prophets with this set up takes a total of 126 turns
If you reverse it and get a GP at 500, and pop your HS next turn, your next one is still at 1000. You have 2 GP's within 2 turns instead of 26 and your third comes around in another 100 turns. So this actually takes 99 turns (you popped HS at 10 faith) and shaves off about 1/4 of the time! Of course the actual savings of time will differ but still the point is valid.
I think this won't be abused though because if you are going for wonders you are usually in a race. You can save 26 turns for example on your next GP, but you have to time exactly your buildings of wonders and great people points to hit this right. If you just researched Theology and you can start the HS and lets say it takes 30 turns to build, but you still need 40 turns worth of fate, if you wait those 10 turns someone else might build it first and you lose the time saved AND the wonder itself along with the GP! Maybe on lower difficulties where you can easily snatch most of the wonders this will happen but in higher difficulties I don't see this being too viable although if things happen to fall in place for you it obviously saves you some time on your next great person.
Thoughts?
