Hello - in the lategame, you often have enough manufacturing/military/research to complete multiple improvements/ships/technologies (hereafter "IST") within one turn. Instead of giving you multiple IST, it appears to give you 1 IST, and save some of the production towards the next IST. It is less of an issue with planetary improvements and buildings, but the way military can be made to scale with manufacturing makes it quite easy to achieve for ships. The lore text of some of the Galactic Wonders and military / manufacturing boosters imply that they are for constructing in a huge manufacturing hub, but if you make such a hub, you end up wasting huge amounts of production each turn because you're producing far more than any one ship or project costs. I've mostly experienced this on 1.7, but 1.8's change to the way population contributes to such things has made it easier to repeat (you no longer need a either a good core-planet location, or a decent core-planet location AND access to galactic wonders, as citizens [especially synthetics] can do a lot of the heavy lifting).
Question: I'm not sure how much any IST overflow stacks over multiple turns, so it'd be nice to know that if possible. Maybe it's not being wasted, but instead infinitely stockpiled, so when I eventually build something like a galactic wonder (or the most expensive dreadnought I can possibly design), all that pent up construction will be released.
Quality of Life Ask: Allow multiple ships, buildings, projects, citizens or improvements to be constructed in one turn, working its way down the build queue and then building as much of anything set to repeat at the end of the queue.
Research is slightly different, but can suffer from the same issue, most prominent when you purposefully neglect something like planetary invasion techs for a long time. I have little idea where overflow research goes; my hunch is that it contributes to, at least, the next turn's technology choice - could anyone tell me? When you gain research during the turn via artifacts, policies etc. it appears that you can research multiple techs in a turn, but I've not seen it happen just based on raw research power. Regarding my above quality of life ask for ships, buildings, projects, citizens and improvements, it is obvious research cannot be treated the same way, as there is no queue, and an interesting research discount system to interact with.
Quality of Life Ask: Insert something truly repeatable into the game to allow you to complete a technology and have the chance to pick a new one if you have the raw research power to over-complete some research. The current 50 control pressure scientists seems a bit steep and unrepeatable for that - maybe a no-cooldown policy costing a lower amount of control, some credits and a Promethium?
If the lack of multiple IST in a single turn is a design choice incentivising more core worlds, thus more shipyards, then I hope bringing the research workaround to your attention is helpful.