This is why ZARA the brand , has such a cult following

Adopted from the following great insight shared by Seth Godin from his book Purple Cow

As it becomes easier to monitor informal consumer networks, the winners will be companies that figure out what’s working fastest – and do it more (and figure out what’s not working – and kill it). Zara, a fast-growing retailer in Europe, changes its clothing line every three or four weeks. By carefully watching what’s working and what’s not, they can evolve their lineup far faster than the competition can ever hope to.