I'm on the consulting side at a B4 and what you're saying is true from the experience of my friends working in audit. The manager level and above should be checking the work quality, but they also have to balance client relationship building (which will advance their careers) with reporting potentially negative results from analysis.

Side note: for anyone looking for a miserable career, choose auditing at a B4. It's a rare combination of overworked and underpaid that has basically everyone racing for the door after a year or two.