Slitherine

Does anyone know how much time it takes for a city to recover its production point capacity after it has been reconquered? Seems to takes ages for me, some cities seem not to recover at all. Note that I'm talking about cities of my nation I conquered back from the enemy, not enemy cities I am occupying.

Bombed cities seem to take about six turns.

I think cities that were occupied or conquered seem to take longer. Maybe ten or twelve.