I've worked in places that didn't bother with code reviews. In the end, they didn't have time for it because all their time was spent desperately trying to keep the mass of poorly-designed, inconsistently implemented legacy code (which included code written the previous week - "legacy" doesn't mean "old") working.

There comes a point where there's no time to stop and start making things better, and you just watch the inevitable disaster come hurtling down the track as people are forced to continue churning out legacy code to keep it going today, knowing that they're just ensuring the final crash will be that much more destructive.

People who don't have time for having large parts of their system only be understood by a single developer.

Why are you in a rush?