The parts worth thinking about you still think about. The parts that you’ve done a million times before you delegate so you can spend better and greater effort on the parts worth thinking about.
Code review is difficult to get right, especially if the goal is judging correctness. Maybe this is a personal failing, but I find being actively engaged to be a critical part of the process; the more time I spend with the code I'm maintaining (and usually on call for!) the better understanding I have. Tedium can sometimes be a great signal for an abstraction!
That's where I'm confused. I've been coding for more than 20 years, and every task I ever did was different from the other ones. What kind of task do you do a million times before realizing that you should script it in bash or Python?