I have always considered Kent Beck understood this the best, the scaling for code reviews as you go to reduced release timeframes is to pair program, that brings the number of people reviewing it down but also increases the understanding for the reviewer. Comprehensive end to end tests are more a replacement for manual quality assurance for regressions.
I am not sure there is a good analogue for reviews in the AI world. The human operating the AI should obviously review everything produced but that is clearly not as good as a second pair of human MK1 eye balls from pair programming.
No need to pair program, you can always send a message to your colleague about the design of the upcoming code, especially if it’s going to impact them or if it’s an area that they’re more familiar with. Waiting till a PR for feedback is wrong IMO.
Code review is not for feedback, it’s for ensuring quality (many eyes on the output) and have a shared involvement in the evolution of the code. The time for feedback is earlier, once you have an idea of the solution.