Being in Big4 for around 2 months, i can confirm that what TS said almost 99% is real but he or she forgot to mention one thing.
Why everybody whom already knew about the horror of Big4 (from anyone who cares to share) still WANTS to join.
Most that goes in armed with the objective of getting as much as they can before they got their professional title (3-4 years) then leave for for good.
The firm ALSO acknowledge this and unleash a full barrage of dung to juniors. The problem is can you absorb and handle it. So the manager thinks how mush s(he) can PUSH you and how much you can PULL from them. Its a situation where "You used me and I use you back". Win-win scenario or scratching your back is gross understatement.

In Big4 if you are dealing with Top40 MYS companies, then it will be true hell & nightmare for auditors (loads & loads of subsidiary to handle + lack of staff ). Some may think that if you finished your job than you can go home, yeah as soon as you finished it, another will kicks in and then another one. Not to mentioned the journey to client (if its far). My client is around 20km from my house (40km back & forth + traffic jam + toll).

You want to start work at 19 ?