It depends on a lot of factors. (distance from capital, culture, governors etc.)

On the closer cities with same culture, with no governors, I have the depleted units (he-he) such as 1 unit of 5 peasants (out of 240) etc. On middle distance provinces, I have one peasant or two peasants. If there's a governor, you normally don't need anything else.

The farthest, newly conquered obviously depends. But I just ease it down as I replace the buildings.