If you have a piece of forest, chop it or place lumber mill? Before I tend to think this as no problem, you shall always chop. However after calculation I start to challenge this conclusion on online speed. Build Lumbermill: +2 production, +1 from trees, so actually +3 production per turn altogether. In late game you can still remove and chop. +1 from Steel and +1 from cybernetics. +1 appeal and becomes +2 after Conservation. Chop: +production right now. Also clear a tile for your district/wonder/other improvements. Suppose you get X production from chopping now, and Y net prod(consider the builder charge cost ) from chopping in late game. There's T turns between now and late game. Suppose value inflates at t% per turn. Simpliest Model: Your profit from chopping now: X (suppose you don't build other things thereafter) Profit from late-game chopping: 3*(1-t%)/t%+Y*(1-t%)^T (ignore bonus from appeal or steel) On online speed suppose X=40, Y=60 and t=7%, T=50, then you get 41.45 from building lumber mill but only 40 from chopping now. So you shall build lumber mill if your citizens do not have a better place to work on. On standard speed suppose X=80, Y=120 and t=5%, T=75, then you get 80 from chopping now but only 59.56 from lumber mill. So you shall chop now. Conclusion: On online speed, if your citizens do not have a better place to work on, you shall build lumber mill instead of chopping right now. Surprisingly this yields a little more than chopping. If they do have better tiles to work then you shall chop. Keep (rain)forests for district adj or Earth Goddess is not always inefficient. On standard speed you shall always chop.