The best-laid schemes of elves and men gang aft agley.
This morning I thought I had the ideal layout for my city with marble, steel and plank manufactories researched. I worked it out so that I would also have 3 level 2 workshops and 0 available workers. Full employment and maximum production -- what could be better? However, I ran up against several problems. First, I did not have enough coins to upgrade the third workshop. Second, I was producing more supplies than I need. Third, I hit a quest that wanted me to upgrade my main hall to level 2.
My first instinct was to kick the can down the road. Persevere with my plan. When I had my barracks built the excess supply problem would be solved by troop production. I planned to substitute the barracks for my marble manufactories (also deleting one planks and two 1x1 culture). However, this meant not only overproducing supplies and underproducing coins until I had researched the barracks, but also would have left me short of culture to upgrade the main hall, which requires 8 culture.
So I took another thought at the problem. Basically, I have too many supplies and not enough gold. The obvious solution would be to replace one supply-producing building with one gold-producing building -- take out my remaining level 1 workshop and replace it with a level 1 residence. This has the advantage of allowing me to upgrade my main hall to level 2 with the excess population while I still have the culture buildings -- which I can still take out when I remove the marble factories in order to place the barracks. I can relocate the culture buildings to the little piece of road currently abutting my marble manufactories, since the barracks won't need road all the way along the edge.
Another advantage to this is that I will have enough population left over to replace two of my steel mills with planks manufactories when I unlock the planks boost and get some relics. A possible problem will be keeping up with supplies to feed my barracks.
Here's my new city:
Edited to add: I have 160 marble, 25 steel and 19 planks so far.