Even before slop coding good code review was hard, because verification is a hard problem. But we have many tools at our disposal to increase confidence without having to go full-on mathematical proof. Human understanding has always been the bottleneck, and as long as the thing you are doing is for humans, humans will have good reasons to want to understand it, so they will remain the bottleneck. This is ok. It’s ok for humans to be the rate-limiter. But don’t go it alone and fry your own brain.