So I'm working on some changes to a feature that a few of our consultants made during the duration of a month. It's really bad. Practically unworkable. Damn I wish we did better code reviews...

Same here. The "chief consultant" was very smart and knowledgeable, and I, a beginner, was responsible for merging stuff.
Most things I didn't understand, and since had "very urgent" tasks of my own, I simply merged if the tests were good, included critical cases, and ran correctly.
Now we see what a spaghetti it is. In some places, totally violates OOP, design patterns, somewhere depends on exceptions to happen which can mean two things, mess of if-else eucalyptus, very dangerous memory leaks (some of which we fixed after prod crashed), and some more.
Fuxkers vanished into thin air after it was done.