Ah, would I guess right to think you enjoy civ1 / civ2 style "optimal city placement" where each gets their full 21 tiles to work? The more one tends to far apart placement, the more important a temple in each city gets by FAR. I've come to VERY MUCH like a 3-step placement between cities. The benefit to defense and war are tremendous. Also, when cities are 3 away that row of border gap you would expect between them will disappear - so you get to work any tile you want without needing a temple. So if I might generalize your thought... build a temple when you want to work more tiles. But as to the when, build a temple WHEN you NEED to work more tiles ASAP. See I don't disagree with a temple per city, and I very frequently eventually get a temple per core or second ring city, it's definitely NOT a high priority unless there is a lux or wheat sitting outside the border. In other words if the tile you pull in won't even be worked until it's size 6 or 7, build the temple when you're size 5 or 6.
So, do you like ICS much Charis, or is this a new fad?
Not trying to knock your playing style, but doesn't it somewhat unbalance the game and break the engine to place cities that close together? Why not just go 'whole hog' and place your cities 2 tiles away instead of three to get the full benefit, hmm?