So far as I know, completing an enhancement with extra resources has no advantage. By this I mean if I'm building a factory which costs 30 manufacturing points, building it in 3 turns at 10 points per turn is the same as building it at 14 points a turn for 3 turns, the extra 12 points is wasted (and would have been better spent on research say).

It's possible to solve this by setting the percentage on manufacturing to the correct amount so that it's exactly 10, however, it means you have to do with whenever your production increases, from population / morale/ enhancements. Basically this means you have to do this calculation every couple of turns. On top of this, if you have military output on the plane you have to fix the ratio of social to military spending. When you have 10+ planets this gets old really quick.

Now, you could just set certain percentages and live with the inefficiencies but I want to squeeze out every bit of production I can

I propose allowing 2 out of the 3 planetary yields to have fixed raw values. The way it would work is you have 3 input fields next to the production wheel, one for each production type. You enter a value for one of the production types and the production wheel becomes another slider with the two endpoints being the other 2 remaining production types. If you enter a second production type the slider disappears and the remaining is allocated 100% to the other production type which becomes read only (otherwise they could allocate < 100% of resources). You could have radio buttons next to each input field that controls/indicates which values are from raw input.

Anything along these lines would be greatly appreciated. I love this game and want to see it grow