The relevant heuristic in NPM supply-chain compromises would be the age of the specific binary. i.e. a freshly released package is riskier than one that's been around for a few days. So perhaps the policy should be that NPM doesn't install new package versions unless they've been public for 24 hours, or there's a signed override from the package repository itself stating that the update fixes a security issue. Of course, that would also require the NPM team have a separate review process for signing urgent security fixes.