[Zooko]

If you have 20 temples with starting dominion 10, then every turn you will get 20 successful temple checks. (I currently think that this means you will get 20 increases *somewhere*, although I could be wrong about that.)

If you have 40 temples with starting dominion 5, then every turn you will get 40 coin flips, and for every "heads" you get one successful temple check. So it will be much more random. Not only could you get lucky or unlucky and get greater or less than 20 successful checks per turn, but also consider that temples exist at different spots on the map -- for example, if there is one particular temple that needs to spread some dominion for you that one temple could easily go for turn after turn after turn without getting a successful temple check.