Generally, the more thought you put in your comics, the better. Planning buildings (as in making real plans for them) is good to avoid logic mistakes later on. But in all honesty, I think in most cases, the reader won't value stuff like that very highly. Or even recognize it.
As for my comic, stuff like that isn't even nessecary, but as a general rule I'd say, you have to see, how much effort you put into one thing and how much it will contribute (visibly) to your comic.