There's a general critique of 4x games that they reach the tipping point prematurely, and then you know the game is won.
For instance: https://steamcommunity.com/app/226860/discussions/1/2595630410193901329/?l=finnish&ctp=3
I'm 70hrs into my current campaign, and prior games would dictate I'd won. So I duly started giving away fleets to allies and generalising my ships defences to eek out the current game for light entertainment. However I've just seen a fleet of 4 huge warships deep in my territory. Looking around the map the show trickle of enemies breaking through has changed to quite a few planets under siege.
Basically, I'm f**ked.
I think if I wind back about 20hr and stop sending heavily armed missionary armadas off to distant sectors, and get back to optimising for my immediate enemy, I can win.
If I'm right I think that speaks to the game staying competitive for longer.