One aspect of managing my economy I find particularly annoying is that the manufacturing points in excess of the amount required to complete an improvement or ship in a turn are simply lost. As another post pointed out, you can only build one thing in one turn irrespective of your manufacturing capacity or the cost of the thing being built. As a consequence you have two choices (1) take the losses on the chin or (2) micromanage the sliders for each planet every time something is built to ensure points aren't lost.

The first option can be quite costly so it's hard to cop if you're trying to play on a high difficulty level. Even early on you can have planets with say 200+ manufacturing and a new improvement might only cost 30. So you're forced into the second option of micromanaging each planet's sliders to minimise the lost points. This is particularly relevant given the game forces you to build a new improvement from the ground up, cycling though each level rather than just paying a total cost for the latest level researched. If you keep your sliders on a fixed amount and have high manufacturing, you'll lose hundreds of points if you decide to build say a new manufactory as it upgrades it way from level one onwards. 

A few points here and there doesn't matter but hundreds on a regular basis seems over the top. The game therefore rewards mindless micro management, which is neither fun nor strategic.

A simple solution would be allow points to carry over and/or allow more than one item to be built each turn. Hard to see that this would change the game balance in any way, and would certainly make it more fun to play.