Working at Zara is...something. I guess one can never be prepared to the amount of stress you have to face once you're in the industry, since you don't really get to see it as a customer.
Even though for the Sale Assistants, working there means having to do about a dozen tasks, at the same time. It teaches you organization skills and how to prioritize tasks, and after a few days you get totally used to work under stress, in a very demanding environment, since during busy hours the shop is probably going to be in a frenzy.
I had friendly and supporting coworkers though, so it always balanced the hardest part of the job. Management can be tough as well, since Zara favorises internal promotion, which is actually a good thing. However, when you get to a manager position, no one really teaches you how to actually manage a team, and things can sometimes get a bit erratic.
I learned a great deal of things when working in Zara though; to be patient, to say no and to assert myself as a person, to work under pressure, to quickly take decisions and, surprisingly, I guess I have learned a bit more regarding team management.