Someone is active on world 1 and has 25 castles with all productions at level 71 and uses all troop bonuses.
Now this player is also active on world 2:
There he gains the same amount of troops times 3.
IF "someone" managed this in the past 3 years on world 2,
you can do it in the remaining 18 month too.
How long did you needed for this task in world 1?
I think you have to redo the math.