NeverarGreat said:
had the effect of freezing innovations on the Starkiller project, which kept the planetary shield tested with the Second Death Star but didn’t boast any other defenses of note.

As the Empire lost more and more ground, their ability to complete the project was impaired, so it took 30 more years and a change of management to finally finish Starkiller Base.

But then how is it that a planet-size shield wasn’t made into a big feature 40 years before TFA in Eadu, but then the suspiciously well funded First Order (whatever a first order is or means) fails to put one around its most cherished weapon?