Even using a program like Campaign Cartographer that uses pre made buildings can take quite a while to make a city if you are looking for one to be made well (ask Clercon about that )

From my experience, making cities is the most time consuming style of map to make, especially when people always seem to want you to put in very specific looking buildings and have the streets laid out a certain way. Then there is the problem of rivers. How do you make the city fit along the waterway, yet still get it too look like the vision the person who commissioned the map wants it to look, because often they have no idea what it should really look like. They always seem to want extra weird things to be happening near the water, like extravagant city/waterfall interactions, and weird, elven like structures near the water that defy the laws of physics, even though the rest of the city might be an Italian theme.