A tile is considered 'improved' when a road, mine, or irrigation is built on it. I suppose one could consider fortresses and airfields 'improved' as well.I just read in another thread that roads don't need to be built to mines... good to know.
So my question is, are all irrigated tiles considered "improved," being farmed, or is it overkill?
No, it's not. However, I tend to automate 'Road-To', 'Railroad-To', and 'Clear Damage/Pollution'.And, is it a good idea to automate workers at any time of the game?
The Clear Damage/Pollution can hurt you too, especially if you have a city that has pollution/damage and that city is seperated from your civ by another civ. They'll try to go to that city and it can be disasterous, especially if you're at war with that civ. Otherwise it's just a pain because the govenor will keep sending workers over there until the damage/pollution is cleared. So you could have a bunch of workers in transit to clear that damage/pollution.