1.61 - Spy mission to destroy production

[Bushface]

I have just tried for the first time to have a spy destroy enemy production, a half-built Factory. The cost was 255 gold. The manual says on p.122 that if the mission succeeds, as it did, then all production will be lost.
This did not happen. The time to complete production increased by 2 turns, and that was all. Since the production rate was only 6 hammers per turn, I consider the expenditure to be hugely disproportionate to the result. Another, later, attempt gave the same "2 extra turns" result.
Has this mission type been intentionally reduced to such a feeble state ? I do not recall seeing it mentioned in the read-me file.
Has anyone else had this problem ?
Has anyone ever been able to afford the cost of trying to destroy a part-built Wonder ??

 

[The Tyrant]

Half of the current production is lost. This means that to get the maximum benefit from destroying production you should wait until the build is near completion. The problem is that the longer you wait, the more expensive it is to even make the attempt. The cost IMO is way out of proportion to the benefit in most cases. Only if the target is the only civ attempting to build a wonder I really want is it even worth trying. Even then it is usually better to let them build the wonder and use that cash for rush-buying enough of a military to take it from them. Spies are useful for scouting and resource denial, but not much else.

 

[Bushface]

Half the production was not lost, just two turns' worth out of many: as I said, twelve hammersworths. Anyway, the destruction of only part of the production is not what the deeply-revered manual says, which is the important point of my post.
Well, I've tried. But never again. I may have a look in a later game to see what the cost would be for knocking a few bells out of Notre Dame or whatever, just for a giggle.