Waves aren't nearly as difficult as you make them out to be.
In fact, I was fighting the hardest waves ever - 2000 threat of core ships, with no turrets unlocked, because of the backwash of nuking and killing the AI homeworld, with 6+ zenith starships.
Not even cross planets are that tough - and this was without unlocking any turrets.
Thing is, you were fighting the hardest waves ever, on your time, on your terms.
Waves individually are not supposed to immanently break your game, then the game would be broken! Waves are about the ebb and flow, the constant threat, the slowly wearing down of your defences until they snap.
Fighting 2000 core ships when you have lightning warheads prepped and ready is one thing.
Fighting 1000 IV ships when your lightning warheads have been vaporized by your fight with the 2000 core ships, and you haven't had time to build them back up is another thing.
Fighting the second 1000 IV ships after that first wave you barely held off because you got lucky.... that's the point of waves.