I'm rarely lazy and usually manual control them, even with 30+ cities, however, if you get lazy and want them to build a generalized "type" of improvement such as:
* make sure you automate the worker to Improve nearest city only, NOT empire wide or they'll make roads everywhere.
* if you want mostly mostly farms go to World Builder and remove mining, pottery, mc, or any other tech that enables work shops.
* if you want mostly cottages then go to World Builder and remove agriculture, mining, and techs that enable work shops, etc.
* if you want mostly work shops then go to World Build and remove pottery, mining (unless you want mines too) and agriculture.
* make sure to have "automated workers leave old improvement" and allow them to chop forest/jungle.
* make sure you automate the worker to Improve nearest city only, NOT empire wide or they'll make roads everywhere.
* if you want mostly mostly farms go to World Builder and remove mining, pottery, mc, or any other tech that enables work shops.
* if you want mostly cottages then go to World Builder and remove agriculture, mining, and techs that enable work shops, etc.
* if you want mostly work shops then go to World Build and remove pottery, mining (unless you want mines too) and agriculture.
* make sure to have "automated workers leave old improvement" and allow them to chop forest/jungle.