vale
Mathematician
I think the problem stems from the fact that you are thinking of slavery as transforming
into
when a more accurate metric is that you are trading population-turns into production. Production in this case refers to both food and hammers and the production gained by a whip is shown in the following table where rows are whip size and columns are original city size:
Whipping something that does not increase happiness when you are at the happy cap always costs at least 10 population turns. There is no cheating the system here. That extra unhappy will always be relevant.
With a happy cap of 5 there are realistically 3 options that have a chance to be best for production:
1. Stagnate at 5: Only relevant in an extremely food poor city.
2. Whip 2 pop every 10 turns from pop 4 - this is sort of the "default mode" and is very easy to sustain as long as you still need workers and settlers.
3. Whip 3 pop every 10 turns from pop 6 - this is harder to sustain as the only early repeatable 3 pop whip is settlers and there usually is a limit to how many settlers are useful.



Whipping something that does not increase happiness when you are at the happy cap always costs at least 10 population turns. There is no cheating the system here. That extra unhappy will always be relevant.
With a happy cap of 5 there are realistically 3 options that have a chance to be best for production:
1. Stagnate at 5: Only relevant in an extremely food poor city.
2. Whip 2 pop every 10 turns from pop 4 - this is sort of the "default mode" and is very easy to sustain as long as you still need workers and settlers.
3. Whip 3 pop every 10 turns from pop 6 - this is harder to sustain as the only early repeatable 3 pop whip is settlers and there usually is a limit to how many settlers are useful.