And, since the cost of change [1] is so much lower at the idea and design stage, most things probably aren’t reaching PR stage that would be likely to seriously fail review (tweaks and details notwithstanding).
That's one of those software engineering facts that people spread as absolute truths that are far from absolute in practice.
It's mostly true, but requirements gathering can be a very expensive process too, and you can lower that cost with a working example. Also, UX designing can get off-track very easily if it's done in a vacuum.
Also related, for some problems, having your software tested before it's even written can bring a lot of productivity to the writing stage. (For some others, it will completely ruin everybody's productivity, so the idea that finding bugs at the "testing" stage is simply "more expensive" fails here too, you don't look at an unmitigated disaster and calls it "more expensive".) For some problems bugs in production are just consequence-free. And in way too many cases you simply can't design some valuable interaction without having people using your ideas on the wild.
TL.DR. that link is a very good rule of thumb, but beware of the exceptions.
Of course, we also had to adjust the way we work to make this feasible. For example, we discuss design and strategy decisions early and often, so that bad designs or obviously wrong choices generally don't make it as far as becoming a pull request, but are rejected already at the idea stage.
Then when we are uncertain, we make the pull request from very rough draft code, and expect to have the big ideas reworked slightly in collaboration with the reviewer, so that once the final pull request is submitted, it's largely in the shape we want, with only minor comments remaining.
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The same thing goes for what you say about time pressure, really. We know why we have the review process in place, and we have hard evidence that it saves us a lot of time and effort in the end, so we don't circumvent it even under pressure.
And we, the software engineers, are the experts who understand this. Management might not always understand it, but that's their problem, not ours. If they start to throw their weight around, that's bad management. Also their problem, in the end.