Just one question regarding this. Some people talk about some whipping rules that you have to wait 10 turns between 2 of them, and that it is not the same if you whip 1,2 or 3 population points. Can you explain this? Or should I start a new thread?
Tofe
Check the Civ Academy as it's much more useful - but to sum up (excluding exploits)
You whip to complete a build and this will use pop to produce 30 hammers (per pop) at a cost of 1 happiness for ten turns. The 30 hammers is reduced if the build is just started.
This is amended by normal modifiers (e.g. forge +25%

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As a granary increase pop growth it effectively reduces the food cost of whipping by 50% so it's best to whip the granary first (then the forge if available).
If you whip while there is still unhappiness from an existing whip (say 5 turns left) then the extra unhappiness from the next whips will last this long PLUS 10 turns (15 in this case).
General Guidelines.
- Use the whip every ten turns if micromanaging (maximises use but prevents unhappiness overlap)
- Ignore this when a captured city comes out of revolt. If the pop is starving due to unhappiness you might as well put it to some use and you want happiness buildings, granarys and forges
- Whip when a build is in its early stages (It's one unhappiness however many pop removed).
- If using the whip for pop managemnet (keeping the city happy) then either build a happiness building and/or whip 2-4 pop. A 1pop whip is happiness neutral (excluding war weariness and other modifiers).