Actually its not wasted there is production overflow but there is a limit of 1 per turn
But it is wasted because the next turn I have another 2000 points of production to send to the shipyard. So now it's 3800 points of "saved" production (2000+1800) but I can still only build a single 200 point ship.
So am I to change the production to something else on the planet while this excess production is used up? I have 100+ colonies, each with a shipyard. That's a lot of micromanagement to keep track off every turn. Is there any display of this "saved" production in game? Or do I need a notepad to keep track of it? Hmm let see, I sent 1000 production to my shipyard 4 turns ago and I build 1x 250 point ship and a 233 point ship, so I have 517 points left, so I can build my 324 point cruiser, but I'll have to remember to send more production the turn after next... now planet 2 of 100...
If there's a gameplay reason for this (eg a single shipyard only has room for 1 ship) then fine, let me build 10 shipyards around my planet and let me split my planet's military production amongst the 10 shipyards. Something you can't do currently. Or say treat shipyards like star bases and let me send a new construction ship to add another "yard" to the base to allow two ships at once, and so on.
Yes, I could build my planets to have lower military productions. Make every planet do everything - influence, food, population, approval, income, research, manufacturing. That way I wouldn't have so much wasted military production. But then it turns every planet into a carbon copy of bland. Why bother with a hyperion shrinker, death furnace, manufacturing capital, or any limited use high quality building at all, if the bonuses they give can't be used?
Isn't part of the fun finding that planet with a base 19 quality. Then researching planetary improvements to increase it to 25. Then getting the perfect adjacency bonuses for your building. Then ringing out every drop of production you can get out of it to turn it into a starship making super machine? It sort of defeats the purpose of specialising planets if you can't actually put all that production to use.