Can people who like the wheel please elaborate why they like it? In my opinion it doesn't add choice, its just extra bookkeeping.
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How is this choice? Isn't specializing by building buildings enough, what does the wheel really add?.
Uhm, you may have misunderstood how the production calculation goes... The population does not produce "1 point of each". Instead the population gives you "raw generic points" that are then split by the wheel into manufacturing, science, and money. That's why the wheel matters.
Consider three very simple specialized planets: Planet M has 4 factories, Planet S has 4 research labs, and Planet E has 4 market centers. Let's say they all have 10 pop and we'll ignore the colony capital and any bonuses be they from adjacencies or from tiles to keep it simple as these just would make the difference even bigger.
Option #1: Empire wide wheel choice 33%/33%/33%
Planet M generates 10 points which is then split into 3.33 manufacturing, 3.33 research, and 3.33 wealth. The 4 factories give +100% bonus to manufacturing so the end result is 6.67 manufacturing, 3.33 research, and 3.33 wealth.
Planet S generates 10 points which is then split into 3.33 manufacturing, 3.33 research, and 3.33 wealth. The 4 labs give +100% bonus to research so the end result is 3.33 manufacturing, 6.67 research, and 3.33 wealth.
Planet E generates 10 points which is then split into 3.33 manufacturing, 3.33 research, and 3.33 wealth. The 4 markets give +100% bonus to wealth so the end result is 3.33 manufacturing, 3.33 research, and 6.67 wealth.
Empire total: 13.33 manufacturing, 13.33 research, and 13.33 wealth.
Option #2: Planetary wheel set to 100% for each planet's specialization.
Planet M generates 10 points which is then split into 10 manufacturing, 0 research, and 0 wealth. The 4 factories give +100% bonus to manufacturing so the end result is 20 manufacturing, 0 research, and 0 wealth.
Planet S generates 10 points which is then split into 0 manufacturing, 10 research, and 0 wealth. The 4 labs give +100% bonus to research so the end result is 0 manufacturing, 20 research, and 0 wealth.
Planet E generates 10 points which is then split into 0 manufacturing, 0 research, and 10 wealth. The 4 markets give +100% bonus to wealth so the end result is 0 manufacturing, 0 research, and 20 wealth.
Empire total: 20 manufacturing, 20 research, and 20 wealth.
Option #2 almost doubles the empire's total production compared to option #1 even though both had specialized planets. With the bonuses the difference would have been even greater and if we increase the population and build more factories, labs, and markets it skyrockets.
The reason for this is that even if you specialize a planet by building specific improvements (factories, labs, markets) in the option #1 two thirds of the planetary population is working on a different area than the planetary specialization and because there are no buildings to give bonuses for them their output keeps small and as a result 2/3 of the workforce potential is wasted. With the planetary wheel you can allocate the entire population to work on the specialized area.