What standard does a court use to set a more relaxed upper bound? What's it relaxed in comparison to, if there was no previous more-rigid bound to begin with?

What standard does a court use to set a more relaxed upper bound? What's it relaxed in comparison to, if there was no previous more-rigid bound to begin with? And if the court did set some very permissive high bound, it could be so porous as to be worthless. And what's worse, the legislature might have little incentive to bother improving it. Plus, arbitrary rulings can get arbitrarily overturned. That's what happened with Roe v Wade. Instead of the legislature enacting a rule, the court did. Then Congress became complacent and failed to "harden" the Supreme Court's ruling. Then when the winds of justice changed, Dobbs came into effect. But had the legislature passed a law codifying a Roe-equivalent standard, the chances of there ever being enough of a majority in both Houses to overturn it plus a president willing to sign a new bill into law would've been minuscule. In short, the less our lives are governed by some random court imposing national standards upon us that were pulled out of the court's honorable ass, the better off we are in the long run.