>>541716
Likely you're not the sort who optimized population talents either. Note that in specialized cities, adding another Librarian/Doctor/etc. can do more than harvesting more resources.
Most solar collectors give you +1-3 energy that is then subdivided according to your Psych/Labs/Econ allocation. This energy's further reduced by inefficiency penalties for being away from your capital. A specialist, on the other hand, generally contributes at least +2 to the particular field (and later game specialists contribute more or to multiple fields), which means that once you're meeting basic nutrient needs it's better to convert extra population into specialists.
Unless the surrounding terrain is ultra-super rich and you can harvest it without raping the eco-damage meter (Monsoon Jungle with forests, for example), don't wait till you max out your work tiles - convert into specialists as soon as you feel you can do it.
An average coastal city that has 8 workers, each one harvesting 2 energy, will harvest 16 energy total. Assuming a 50/50 Labs/Econ split, you'll put 8 energy into labs and 8 into Econ. Not bad... but if you're far away from the capital, you might only actually get 12 energy after inefficiency, which means a net gain of 6 labs, 6 econ. Still not bad, but what if you want to maximize Labs output to get tech faster?
Given the same scenario, converting to 4 harvesters and 4 librarians might give you more. 8 energy from the harvesters, maybe reduced to 6 after inefficiency split between Labs/Econ. Librarians give an unmodified +2 to labs, so 8 straight to Labs. Overall your output is 11 Labs, 3 Econ. Note that overall, this is effectively 14 energy, still more output than a straight 12 energy split 50/50!
This becomes far more important as the numbers and penalties get bigger.